the following detailed description of the present subject matter refers to subject matter in the accompanying drawings which show , by way of illustration , specific aspects and embodiments in which the present subject matter may be practiced . these embodiments are described in sufficient detail to enable those skilled in the art to practice the present subject matter . references to “ an ”, “ one ”, or “ various ” embodiments in this disclosure are not necessarily to the same embodiment , and such references contemplate more than one embodiment . the following detailed description is demonstrative and not to be taken in a limiting sense . the scope of the present subject matter is defined by the appended claims , along with the full scope of legal equivalents to which such claims are entitled . certain implantable devices have been developed to operate in remote portions of a patient . these remote devices include , for example , remote sensors , neurostimulation devices , and other devices . depending on the implant location , remote devices must be small enough to fit into various confined areas of the human body . the requirements for such devices are unique compared to other applications because their size must be small enough to be noninvasive . therefore , the size of these remote devices is typically considerably smaller than common devices , like cardiac rhythm management devices . the limited size of remote devices correspondingly limits the size of the components of the device , including its power source . while the power source is not as large , the power demands of these remote devices must still be satisfied . large batteries , with volumes on the order of 1 cubic centimeters or greater , are commonly used for devices such as cardiac pacemakers and defibrillators . remote devices benefit from batteries which are a fraction of that size . battery sizes smaller than 1 cubic centimeter are contemplated by the present subject matter . the present subject matter extends to thin film batteries . various thin film batteries are formed using vapor deposition of electrode and electrolyte materials onto a semiconductor substrate ( such as silicon ). however , achieving battery sizes small enough to meet the requirements of remote devices using thin film technology is problematic . either very thick layers of deposition are required , or a number of thin film batteries must be stacked and connected in parallel . in either case , rendering the thin film battery or batteries into a cylindrical shape , which is often a requirement of remote device power sources , can be difficult . an improved power source for remote sensing and neurostimulation is needed . this disclosure provides an efficient electrochemical power source for remote implantable medical devices . battery chemistry and technology from large battery applications are adapted to appropriately size power sources for remote implantable medical devices , while ensuring that power and capacity demands of the devices are satisfied . fig1 illustrates a block diagram of an electrochemical power source for use in a remote implantable medical device , according to various embodiments . the electrochemical power source 100 includes a housing 102 geometrically defined to reside within a remote implantable medical device . the power source 100 includes at least one anode 103 , at least one cathode 107 , and an electrolyte 105 within the housing . in various embodiments , the electrochemical power source has a displacement volume of below 0 . 024 cubic centimeters and is adapted to provide electrical current used to operate the device . according to some embodiments , the remote implantable medical device includes a remote implantable sensor . the remote implantable medical device includes a remote neurostimulation device , according to some embodiments . the electrochemical power source is rechargeable in some embodiments . some examples of methodologies for device battery layouts are provided in u . s . patent application ser . no . 11 / 264 , 966 , filed on nov . 2 , 2005 , entitled “ system and method for sealing battery separator ”, which is commonly assigned and herein incorporated by reference in its entirety . according to various embodiments , the power source has a cylindrical shape . non - cylindrical shapes ( or form factors ) additionally are covered by the present subject matter . in some embodiments , the remote implantable medical device sized for placement in a blood vessel . in some of these embodiments , measurements are taken so that flow at the implant site can be modeled . some embodiments use statistical models of the human body to model flow at the implant site . in various embodiments , the power source is sized to enable an implantable device which is shaped to provide the following benefits : reduced hydrodynamic drag , reduced turbulence , reduced stagnation and / or reduced fluid sheer stress . in various embodiments , the power source is small to enable such benefits . in some embodiments , the power source is shaped to conform to an interior of a device shaped to provide such benefits . various embodiments of the present subject matter include implantable medical devices . in various embodiments , implantable sensors are discussed . implantable sensors , in various embodiments , are self - powered measurement devices . in some embodiments , these devices provide a wireless signal to one or more receivers . receivers may be located in vivo or ex vivo . a transceiver relationship is additionally possible , in various embodiments . because of their implanted nature , implantable sensors should be as compact as possible . device profile should be optimized for a minimally invasive implantation . as some embodiments are intended for endovascular use , several design parameters are important . for example , it is important to provide an implantable device which reduces hydrodynamic drag , turbulence , fluid sheer stress , and / or stagnation . an improper design in light of these phenomena can lead to the creation of an embolus , and can lead to occlusion of the vessel caused , in part , by the implanted device . the present subject matter provides an implantable medical device , in various embodiments , which features an improved profile for implanted use . in some embodiments , the profile provides improved performance for endovascular use . fig2 shows a schematic of an implantable medical device 200 , according to one embodiment of the present subject matter . various embodiments of the present subject matter include electronics 204 . additionally , in various embodiments , a power source 202 is included . the implantable device 200 can be symmetrical along three , two , or no axes , in various embodiments . in various embodiments , the device includes a device shell 206 . in some of these embodiments , the device shell 206 is hermetically sealed . in some embodiments , the device shell 206 is partially defined by a case which houses electrodes for the power source 202 . a power source 202 , in various embodiments , includes a battery . in additional embodiments , the power source 202 includes a capacitor . electronics 204 , in various embodiments , include various components . some embodiments include components adapted to communicate energy with devices external to the implantable medical device 200 . in some of these embodiments , the energy is communicated wirelessly . embodiments within the present subject matter include , but are not limited to , ultrasonic transducers , inductive transducers , and other wireless transducers . additional components are included as well . electronics 204 include , in various embodiments , components for wireless communication of information to devices external to the implantable medical device . additionally , in various embodiments , electronics 204 include sensor electronics which communicate data . some of these embodiments include a pressure transducer . also , in some embodiments , electronics 204 include stimulation electronics . some of these embodiments include neurostimulation electronics . some embodiments include a processor interconnected to other components to assist other components in communicating with each other . these components are not an exhaustive or exclusive list covering the scope of the present subject matter , and additional components not expressly listed herein additionally fall within the present scope . in various embodiments , the device shell includes a profile which improves fluid flow . in some embodiments , the shell profile reduces hydrodynamic drag , turbulence , fluid sheer stress , and / or stagnation . in some embodiments , the shell is elongate . some of these embodiments include a shell which is elongate , and which includes portions which have a circular cross section . an elongate shell is useful for implantation in a blood vessel in a manner which reduces hydrodynamic drag , turbulence , fluid sheer stress , and / or stagnation . various embodiments include applications which have a profile adapted for implantation in a vein or in an artery . various embodiments use an elongate shell in which the power source 202 and electronics 204 are stacked in a column along the interior of the elongate shell . in additional embodiments , the power source 202 and the electronics 204 are disposed side - by - side along the length of the elongate shell . in various embodiments , hydrodynamic drag , turbulence , fluid sheer stress , and / or stagnation are determined using computational fluid dynamics . in some embodiments , measurements are taken of a target implant site . in some of these embodiments , the measurements are used to determine the shape of an implantable medical device which reduces hydrodynamic drag , turbulence , fluid sheer stress , and / or stagnation . some embodiments do not base modeling for reduced hydrodynamic drag , turbulence , fluid sheer stress , and / or stagnation on the measurement of an individual implant site . in some embodiments , the shape of the shell is determined based on reduced hydrodynamic drag , turbulence , fluid sheer stress , and / or stagnation in a statistically significant hypothetical model . for example , in some embodiments , a patient population is measured , and a model having blood - flow characteristics which typify the population is created . this model is used in the creation of a shell which reduces hydrodynamic drag , turbulence , fluid sheer stress , and / or stagnation , in various embodiments . in some of these embodiments , a power source 202 is created to fill a portion of the interior of the implantable medical device in a manner which limits the amount of unused space . in some of these embodiments , the power source 202 is made from a stack of substantially planar power source 202 electrodes . some embodiments use a stack of substantially planar power source 202 electrodes having different layers perimeters . such a stack can have contours which are adapted to efficiently adhere to all or a portion of the interior space of the implantable medical device . additional embodiments can use wound electrodes . battery embodiments having shapes which are determined as a function of improved fluid flow also fall within the scope of the present scope , including , but not limited to , battery embodiments having a prismatic shape , a generally cylindrical shape , and other shapes fall within the present scope . in various embodiments , the implantable medical device 200 is adapted for reduced invasion during surgery . for example , in some embodiments , a profiles is used which delivers reduced tissue damage . various embodiments include a profile having reduced tissue damage includes an elongate device having a length of from about 5 millimeters to about 10 millimeters . devices up to 5 millimeters are possible , in various embodiments . additional embodiments use devices of over ten millimeters . additionally , various embodiments includes a profile which an average width of from about 1 millimeter to about 3 millimeters . some embodiments are sized up to 1 millimeter . additional embodiments are sized over 3 millimeters . various embodiments are cylindrical , and are from about 5 to 10 millimeters long , and about 1 to 3 millimeters in diameter . some embodiments are around 2 . 5 millimeters in diameter . some embodiments are greater than 3 millimeters in diameter . additionally , some embodiments are longer than 10 millimeters . in some embodiments , the implantable medical device is elongate , with a proximal portion and a distal portion . in various embodiments , during implantation , the device is grasped at the proximal portion , and the distal portion is led through vasculature . in some of these embodiments , the distal portion has one or more edges . edges , in various embodiments , are rounded to reduce tissue damage during implantation . profiles which reduce tissue damage may also be included . for example , implantable medical devices having a parabolic distal portion fall within the present scope . some of these embodiments are bullet shaped . other profiles not expressly listed herein are additionally encompassed by the present scope . in one process of the present subject matter , a profile of the implantable medical device 200 is determined as a function of power and size requirements . power requirements , in various embodiments , are determined by the number of energy use events which occur during implantation . in some embodiments around 33 milliamp - hours are consumed per month , for example . it is understood that other devices using other power and size requirements are contemplated to be within the scope of this invention . in some of these embodiments , power requirements are further defined by battery efficiency . battery efficiency , in various embodiments , is a function of self - leakage . power requirements are further determined by battery type . for example , some embodiments use primary batteries . some embodiments use secondary batteries . secondary batteries enable recharging . recharging , in various embodiments , is depending on patient compliance . recharging frequency should be reduced to increase patient satisfaction . in an additional process of the present subject matter , a power requirement is determined and a power source 202 profile is selected to satisfy the power requirement and to satisfy a size requirement which reduces invasiveness . in some of these embodiments , a power management algorithm is developed to comply with these constraints . in some of these embodiments , a secondary power source 202 is used . in some of these embodiments , a power source 202 charging algorithm is used to improve power source 202 profile and the reduce requirements to a patient to visit a clinic to recharge the power source 202 . in various embodiments , an iterative process of selecting a profile , and selecting a power management algorithm is used to determine the final profile of power source 202 which meets predetermined therapeutic requirements . various embodiments incorporate battery chemistries compatible with the present configurations . embodiments within the present scope include , but are not limited to , at least one of a metal oxide , a metal sulfide , a metal selenide , a metal halide , a metal oxyhalide compound , and corresponding lithiated forms . some of these embodiments include at least one of manganese , vanadium , silver , molybdenum , tungsten , cobalt , nickel , chromium , and main group compounds such as carbon monofluoride and iodine . additionally , some embodiments include at least one of carbon , lithium , sodium , potassium , rubidium , cesium , magnesium , calcium , strontium , barium , tin , zinc or silver . primary battery chemistry embodiments fall within the present scope . additionally , secondary battery chemistry embodiments fall within the present scope . in some embodiments a power source of an implantable medical device includes a plurality of batteries connected in series , parallel or a combination of series and parallel . various electrode constructions fall within the present scope . embodiments compatible with the present subject matter include monolithic electrodes , pelleted electrodes , and other electrodes which have a solid shape . pelleted electrodes , in various embodiments , include pellets formed from compressed powder , dough or slurry . some electrode embodiments are formed from a tightly wound ribbon which is wound unto itself without an insulator to separate progressive wraps from one another . additionally , some embodiment include an electrode onto which is pressed or coated an electronically conductive material . other electrode configuration embodiments compatible with the present subject matter additionally fall within the present scope . additionally , various battery profiles using these electrodes fall within the present scope . embodiments with the present scope include , but are not limited to , batteries having a cylindrical shape , batteries having a prismatic shape , batteries having a button shape , and batteries having other shapes . in some examples , batteries have shape which is determined as a function of the shape &# 39 ; s impact on reducing blood flow . in some examples , batteries have shape which is determined as a function of the shape &# 39 ; s impact on reducing tissue damage during implantation . fig3 shows a side view of an implantable medical device having a semi - spherical shaped portion , according to one embodiment of the present subject matter . in various embodiments , a protrusion 302 extends from the main portion 304 of the implantable device . the protrusion 302 is useful , in various embodiments , for positioning the device in a target implant site . for example , in some embodiments , a positioning lead grasps the device at protrusion 302 . protrusion 302 includes a texture , in various embodiments . for example , some embodiments of protrusion 302 include knurling . in various embodiments , the positioning lead positions the device while connected to the implantable device at the protrusion 302 . in various embodiments , the positioning lead releases the implantable medical device . in various embodiments , the protrusion 302 provides a handle which is compatible with a clasp of a positioning lead , but in some embodiments , a protrusion is not included , and a positioning lead grasps the main body of the implantable medical device . fig4 shows a side view of an implantable medical device having a polyhedral portion , according to one embodiment of the present subject matter . the implantable medical device pictured includes a protrusion 402 , and a main portion 404 . the main portion 404 is shaped like a polyhedron , in some embodiments . in additional embodiments , it is cone shaped . fig5 shows a side view of an implantable medical device having a polyhedral portion , according to one embodiment of the present subject matter . the implantable medical device pictured includes a protrusion 502 , and a main portion 504 . the pictured embodiment has a chisel shape . fig6 shows a side view of an implantable medical device , according to one embodiment of the present subject matter . the implantable medical device pictured includes a protrusion 602 , and a main portion 604 . in various embodiments , the implantable medical device has a distal portion which is shaped like a cone with the tip missing . in additional embodiments , the main portion 604 is a polyhedron . in some embodiments , the main portion 604 is bullet shaped . the shapes described and pictured herein do not define an exhaustive or an exclusive list of the possible shapes within the present subject matter . additional shapes fall within the present scope . for example , additional shapes which reduce hydrodynamic drag , turbulence , fluid sheer stress , and / or stagnation , fall within the present scope . in various embodiments , an implantable medical device includes an improved shape enabled by the use of a battery which includes stacked electrodes . in some of these embodiments , the contour of the stack is non - linear , enabling the stack to occupy space within an implantable medical device efficiently . additionally , in some embodiments , the battery is a coil . fig7 shows a side view of an implantable medical device , according to one embodiment of the present subject matter . the device 702 includes a first portion 704 which has a first profile shaped as a function of hydrodynamic drag , turbulence , fluid sheer stress , and / or stagnation . the device additionally includes a second portion 706 which has a second profile shaped as a function of hydrodynamic drag , turbulence , fluid sheer stress , and stagnation . blood flow is known to be bidirectional in a blood vessel . additionally , as the heart pumps blood , the rate of blood flow of blood varies across a cross section of a blood vessel . therefore , improved medical device embodiments are designed to offer increased performance in reducing hydrodynamic drag , turbulence , fluid sheer stress , and / or stagnation . the present subject matter includes a device having a first portion 704 which is shaped to offer improved compatibility with blood flow direction 708 , in various embodiments . in some of these embodiments , the present subject matter includes a second portion 706 which is shaped to offer improved compatibility with blood flow direction 710 . blood flow direction 708 is approximately collinear with blood flow direction 710 , in various embodiments . fig8 shows a side view of an implantable medical device , according to one embodiment of the present subject matter . in various embodiments , the device includes a first shell portion 803 . in additional embodiments , a second shell portion 805 is attached to the first shell portion 803 . the first shell portion 803 and the second shell portion 805 are hermetically sealed to one another with a hermetic seal 804 , in various embodiments . hermetic seals include welds , resins , and additional types of known hermetic seals . in various embodiments , the first shell portion 802 doubles as a case for a battery . for example , in some embodiments , a battery anode and cathode are disposed in a case 802 . battery case embodiments include a drawn case portion mated to another case portion , in some examples . in some of these examples , a drawn case portion is sealed to another case portion with a battery case seal . in embodiments where the implantable medical device 801 requires a hermetically sealed exterior , and the battery case seal is exposed to the environment of the implantable medical device , the battery case seal is hermetic . in embodiments where the battery case seal is not exposed to the environment , the battery case seal may not be hermetic . for example , in some non - hermetic embodiments , the battery case seal is adapted to resist the flow of battery electrolyte . the implantable medical device 801 , in various embodiments , includes an optional cavity 810 . in various embodiments , the cavity passes through the implantable medical device 801 . in additional embodiments , the cavity does not pass through the implantable medical device 801 , but instead defines an interior cavity . an optional cavity 810 , in various embodiments , is defined by a cylindrical opening which is concentric to an overall cylindrical shape of the implantable medical device 801 , in some embodiments . some configurations of the present subject matter are toroidally shaped . some shapes of the present subject matter resemble an extruded toroid . in various embodiments , the cavity is irregular . fig9 shows a perspective view of an implantable medical device , according to one embodiment of the present subject matter . in various embodiments , an implantable medical device 901 includes a first portion 904 and a second portion 902 . in some embodiments , the second portion 902 includes electronics . some of these embodiments include pressure transducers . in additional embodiments , the second portion 902 includes a battery . in some of the embodiments , the battery is housed in the case which is the same as the exterior of the second portion 902 . in some embodiments , the first portion 904 includes electronics . some of these embodiments include pressure transducers . in additional embodiments , the first portion 904 includes a battery . in some of the embodiments , the battery is housed in the case which is the same as the exterior of the first portion 904 . in some embodiments , the first portion 904 extends through the second portion 902 . in some of these embodiments , a cavity extends through the first portion 904 . a cavity assists in improving performance with respect to hydrodynamic drag at the implant site , turbulence at the implant site , fluid sheer stress at the implant site , and / or stagnation at the implant site . for example , in some embodiments , a cavity discourages emboli formation . returning to fig1 , according to various embodiments , an outer surface of the housing is coated with a biocompatible coating . some of these embodiments include drug eluting coatings . some of these coatings reduce various unwanted effects , such as stenosis . additionally , some eluting coatings deliver chemical therapy . examples of biocompatible coatings are provided in u . s . pat . no . 6 , 664 , 335 , entitled “ polyurethane elastomer article with ‘ shape memory ’ and medical devices therefrom ”, which is commonly assigned and incorporated herein by reference in its entirety . other types of coatings are contemplated by the present subject matter . various cathode configurations are contemplated by the present subject matter . the physical forms of cathode 107 used in various embodiments include , but are not limited it , compressed powder , dough andor slurry . in various embodiments , the cathode can be formed by the processes including , but not limited to , disposing the cathode directly in the battery container , pressing the cathode into the battery container , and / or pressing the cathode onto an electrically conductive material . cathodes compositions contemplated by the present subject matter include , but are not limited to , one or more of the following : metal oxide , metal sulphide , metal selenide , metal halide , metal oxyhalide compound and / or their corresponding lithiated forms . the cathode may include manganese , vanadium , silver , molybdenum , tungsten , cobalt , nickel , or chromium . the cathode may also include a main group compound such as carbon monofluoride or iodine . other compositions of the cathode are within the scope of this disclosure . anodes of the present subject matter include , but are not limited to , carbon and / or metals . anode compositions include , but are not limited to , one or more of the following : metals such as lithium , sodium , potassium , rubidium , cesium , magnesium , calcium , strontium , barium , tin , zinc and / or silver , and other anode compositions not expressly recited herein . the electrochemical power source 100 is capable of supporting charging and discharging currents on the order of 10 ma to 1 pa , according to various embodiments . waveforms contemplated by the present subject matter include , but are not limited to , continuous , pulsed and other waveforms . additional levels of charging and discharging currents can be supported using the disclosed power source without departing from the scope of the disclosure . various electrochemical power sources of the present subject matter are designed and the components and chemistries selected to ensure a reduced level of self - discharge . some embodiments are constructed to encourage detectable state of charge or depth of discharge ( dod ) indicated when monitoring open - circuit cell voltage ( ocv ). various power sources of the present subject matter are designed to have a near - linear ocv vs . dod curve for the first 60 - 90 % of dod . fig1 illustrates a block diagram of an implantable medical device , according to one embodiment . the implantable medical device 1001 includes electronics 1008 . the implantable medical device 1001 also includes at least one electrochemical power source 1000 adapted to provide electrical current to the electronics . a power source 1000 , in various embodiments , includes a battery . in additional embodiments , the power source 1000 includes a capacitor . the power source 1000 includes a housing 1002 geometrically defined to reside with the remote implantable medical device . the power source also includes at least one anode 1003 , at least one cathode 1007 , and an electrolyte 1005 within the housing . according to various embodiments , the power source has a displacement volume of below 0 . 024 cubic centimeters . according to various embodiments , the at least one power source includes multiple power sources electrically connected in series , connected in parallel , or connected in a combination of series and parallel , to provide the necessary electrical current to power the remote implantable medical device . the electronics 1008 includes sensor circuitry , stimulation circuitry , and combinations thereof , according to various embodiments of the present subject matter . according to various embodiments , the electronics 1008 includes sensor circuitry adapted to provide diagnostic functions . some of these embodiments include a pressure transducer . embodiments within the present subject matter additionally include , but are not limited to , ultrasonic transducers , inductive transducers , and / or other transducers . the electronics 1008 may also include stimulation circuitry adapted to provide a therapeutic function , such as neurostimulation circuitry adapted to provide neurostimulation therapy . electronics 1008 , in various embodiments , include various components . some embodiments include components adapted to communicate other devices . in some embodiments , communications are conducted wirelessly . communications with devices external to the implantable medical device 1001 are contemplated by the present subject matter . additionally , wireless communications with receivers located in vivo are contemplated . some embodiments include a processor interconnected to other components to assist components in communicating with each other . this list of components is not an exhaustive or exclusive list covering the present subject matter , and additional components not expressly listed herein additionally are contemplated . the implantable device 1001 can be symmetrical along three , two , or no axes , in various embodiments . in various embodiments , the device includes a device housing 1002 . in some of these embodiments , the device housing 1002 is hermetically sealed . in some embodiments , the device housing 1002 is partially defined by a case which houses electrodes for the power source 1000 . embodiments of the present subject matter include a housing which has a shape which is modeled to achieve a fluid flow objective , in various embodiments . in some of these embodiments , a power source has a shape which is compatible with said device housing shape . in various embodiments , the device housing includes a profile which improves fluid flow . in some embodiments , the housing profile reduces hydrodynamic drag , turbulence , fluid sheer stress , and / or stagnation . in some embodiments , the housing is elongate . some of these embodiments include a housing which is elongate , and which includes portions which have a circular cross section . an elongate housing is useful for implantation in a blood vessel in a manner which reduces hydrodynamic drag , turbulence , fluid sheer stress , and / or stagnation . various embodiments include applications which have a profile adapted for implantation in a vein or in an artery . various embodiments use an elongate housing in which the power source 1000 and electronics 1008 are stacked in a column along the interior of the elongate housing . in various embodiments , hydrodynamic drag , turbulence , fluid sheer stress , and / or stagnation are determined using computational fluid dynamics . in some embodiments , measurements are taken of a target implant site . in some of these embodiments , the measurements are used to determine the shape of an implantable medical device which reduces hydrodynamic drag , turbulence , fluid sheer stress , and / or stagnation . some embodiments do not base modeling for reduced hydrodynamic drag , turbulence , fluid sheer stress , and / or stagnation on the measurement of an individual implant site . in some embodiments , the shape of the housing is determined based on reduced hydrodynamic drag , turbulence , fluid sheer stress , and / or stagnation in a statistically significant hypothetical model . for example , in some embodiments , a patient population is measured , and a model having blood - flow characteristics which typify the population is created . this model is used in the creation of a housing which reduces hydrodynamic drag , turbulence , fluid sheer stress , and / or stagnation , in various embodiments . in some of these embodiments , a power source 1000 is created to fill a portion of the interior of the implantable medical device in a manner which limits the amount of unused space . in some of these embodiments , the power source 1000 is made from a stack of substantially planar power source 1000 electrodes . some embodiments use a stack of substantially planar power source 1000 electrodes having different layers perimeters . such a stack can have contours which are adapted to efficiently adhere to all or a portion of the interior space of the implantable medical device . additional embodiments use wound electrodes . battery embodiments having shapes which are determined as a function of improved fluid flow also fall within the scope of the present scope , including , but not limited to , battery embodiments having a prismatic shape , a generally cylindrical shape , and other shapes fall within the present scope . in various embodiments , the implantable medical device 201 is adapted for reduced invasion during surgery . for example , in some embodiments , a profile is used which delivers reduced tissue damage . various embodiments include a profile having reduced tissue damage includes an elongate device having a length of from about 5 millimeters to about 10 millimeters . devices up to 5 millimeters are possible , in various embodiments . additional embodiments use devices of over 10 millimeters . additionally , various embodiments include a profile which has an average width of from about 1 millimeter to about 3 millimeters . some embodiments are sized up to 1 millimeter . additional embodiments are sized over 3 millimeters . various embodiments are cylindrical , and are from about 5 to 10 millimeters long , and about 1 to 3 millimeters in diameter . some embodiments are around 2 . 5 millimeters in diameter . some embodiments are greater than 3 millimeters in diameter . additionally , some embodiments are longer than 10 millimeters . in some embodiments , the implantable medical device is elongate , with a proximal portion and a distal portion . in various embodiments , during implantation , the device is grasped at the proximal portion , and the distal portion is led through vasculature . in some of these embodiments , the distal portion has one or more edges . edges , in various embodiments , are rounded to reduce tissue damage during implantation . profiles which reduce tissue damage may also be included . for example , implantable medical devices having a parabolic distal portion fall within the present scope . some of these embodiments are bullet shaped . other profiles not expressly listed herein are additionally encompassed by the present scope . in one process of the present subject matter , a profile of the implantable medical device 1001 is determined as a function of power and size requirements . power requirements , in various embodiments , are determined by the number of energy use events which occur during implantation . in some embodiments around 33 milliamp - hours are consumed per month , for example . it is understood that other devices using other power and size requirements are contemplated to be within the scope of this invention . in some embodiments , power requirements are further defined by battery efficiency . battery efficiency , in various embodiments , is a function of self - leakage . power requirements are further determined by battery type . for example , some embodiments use primary batteries . some embodiments use secondary batteries . secondary batteries enable recharging . recharging , in various embodiments , is depending on patient compliance . recharging frequency should be reduced to increase patient satisfaction . in an additional process of the present subject matter , a power requirement is determined and a power source 1000 profile is selected to satisfy the power requirement and to satisfy a size requirement which reduces invasiveness . in some of these embodiments , a power management algorithm is developed to comply with these constraints . in some of these embodiments , a secondary power source 1000 is used . in some of these embodiments , a power source 1000 charging algorithm is used to improve power source 1000 profile and the reduce requirements to a patient to visit a clinic to recharge the power source 1000 . in various embodiments , an iterative process of selecting a profile , and selecting a power management algorithm is used to determine the final profile of power source 1000 which meets predetermined therapeutic requirements . fig1 illustrates a block diagram of an implantable medical device having sensing and stimulating capabilities , according to one embodiment . the implantable medical device 1101 includes sensor circuitry 1140 adapted to provide a diagnostic function , such as sensing pressure , blood flow , or other measurable medical parameter . the implantable medical device 1101 also includes stimulator circuitry 1135 adapted to provide a therapeutic function . an example of stimulator circuitry 1135 includes neurostimulation circuitry adapted to provide neurostimulation therapy , while other types of stimulator circuitry are within the scope of this disclosure . the implantable medical device 1101 further includes at least one electrochemical power source 1100 adapted to provide electrical current to the stimulator and sensor circuitry . the power source 1100 includes a housing 1102 geometrically defined to reside with the remote implantable medical device . the power source also includes at least one anode 1103 , at least one cathode 1107 , and an electrolyte 1105 within the housing . according to various embodiments , the power source has a displacement volume of below 0 . 024 cubic centimeters . fig1 illustrates a block diagram of a system with a device having an electrochemical power source such as illustrated in fig1 , according to one embodiment . the system includes a device 1201 , an electrical lead 1220 coupled to the device 1201 , and at least one electrode 1225 . the device includes a controller circuit 1205 , a memory circuit 1210 , a telemetry circuit 1215 , and a neural stimulation circuit 1235 . the device also includes a battery 1200 having a housing geometrically defined to reside with a remote implantable medical device . the battery 1200 also includes at least one anode , at least one cathode , and an electrolyte within the housing . the battery 1200 has a displacement volume of below 0 . 024 cubic centimeters . the battery is adapted to provide sufficient electrical power to operate the device . the battery may be rechargeable , according to an embodiment . the controller circuit 1205 is operable on instructions stored in the memory circuit to deliver an electrical neural stimulation therapy . therapy is delivered by the neural stimulation circuit 1235 through the lead 1220 and the electrode ( s ) 1225 . the telemetry circuit 1215 allows communication with an external programmer 1230 . the programmer 1230 can be used to adjust the programmed therapy provided by the device 1201 , and the device can report device data ( such as battery and lead resistance ) and therapy data ( such as sense and stimulation data ) to the programmer using radio telemetry , for example . according to various embodiments , the device 1201 senses one or more physiological parameters and delivers neural stimulation therapy . the illustrated system also includes sensor circuitry 1240 that is coupled to at least one sensor 1245 . the controller circuit 1205 processes sensor data from the sensor circuitry and delivers a therapy responsive to the sensor data . fig1 illustrates a block diagram of a programmer such as illustrated in the system of fig4 or other external device to communicate with the device ( s ), according to one embodiment . an example of another external device includes personal digital assistants ( pdas ) or personal laptop and desktop computers in a wireless patient monitoring network . the illustrated device 1322 includes controller circuitry 1345 and a memory 1346 . the controller circuitry 1345 is capable of being implemented using hardware , software , and combinations of hardware and software . for example , according to various embodiments , the controller circuitry 1345 includes a processor to perform instructions embedded in the memory 1346 to perform a number of functions , including communicating data and / or programming instructions to the implantable devices . the illustrated device 1322 further includes a transceiver 1347 and associated circuitry for use to communicate with an implantable device . various embodiments have wireless communication capabilities . for example , various embodiments of the transceiver 1347 and associated circuitry include a telemetry coil for use to wirelessly communicate with an implantable device . the illustrated device 1322 further includes a display 1348 , input / output ( i / o ) devices 1349 such as a keyboard or mouse / pointer , and a communications interface 1350 for use to communicate with other devices , such as over a communication network . fig1 illustrates a flow diagram of a method for manufacturing an electrochemical power source for use in an implantable medical device , according to one embodiment . according to various embodiments , the method 1400 includes providing a housing geometrically defined to reside with an implantable medical device , at 1405 . the method also includes providing at least one anode , at least one cathode , and an electrolyte within the housing , at 1410 . according to various embodiments , the power source has a displacement volume of below 0 . 024 cubic centimeters and is adapted to provide electrical current used to operate the device . according to various embodiments , providing the cathode includes providing a cathode including compressed powder , dough and / or slurry . the cathode can be formed directly in the battery container or pressed or coated onto an electrically conductive material . in various embodiments , the cathode includes at least one metal oxide , metal sulphide , metal selenide , metal halide or metal oxyhalide compound or their corresponding lithiated forms . the cathode may include manganese , vanadium , silver , molybdenum , tungsten , cobalt , nickel , or chromium . the cathode may also include a main group compound such as carbon monofluoride or iodine . other compositions of the cathode are within the scope of this disclosure . in this method , providing the anode includes providing an anode including carbon or a metal , according to various embodiments . the anode may include metals such as lithium , sodium , potassium , rubidium , cesium , magnesium , calcium , strontium , barium , tin , zinc or silver . other compositions of the anode are within the scope of this disclosure . one of ordinary skill in the art will understand that , the modules and other circuitry shown and described herein can be implemented using software , hardware , and combinations of software and hardware . as such , the illustrated modules and circuitry are intended to encompass software implementations , hardware implementations , and software and hardware implementations . the methods illustrated in this disclosure are not intended to be exclusive of other methods within the scope of the present subject matter . those of ordinary skill in the art will understand , upon reading and comprehending this disclosure , other methods within the scope of the present subject matter . fig1 shows a cross section of a bobbin battery , according to one embodiment of the present subject matter . bobbin batteries benefit from having fewer inactive components and / or less of an inactive component . for example , some bobbin battery embodiments have less separator . additionally , some bobbin battery embodiments have less current collector . while bobbin batteries can provide a reduced discharge rate over other battery configurations for a given size , they provide improved performance in applications which are less sensitive to discharge rate . the improved performance is due , in part , to the reduction in inactive materials , which can lead to reduced size . a bobbin configuration includes a casing 1506 . in various embodiments , the bobbin configuration includes an anode 1508 . in various embodiments , the anode 1508 is electrically interconnected with the casing 1506 . in various embodiments , the bobbin configuration includes a cathode 1510 . the cathode 1510 , in various embodiments , is connected to a terminal 1516 using a current collector 1512 . separator 1514 is disposed between the anode 1508 and the cathode 1510 . the polarity of components discussed herein is selected to assist in explanation , and can be reversed without departing from the present scope of embodiments . various embodiments require sealing the internal components of the bobbin configuration . in some of these embodiments , a seal 1502 is disposed between the terminal 1516 and the casing 1506 . in various embodiments , the seal 1502 resists electrical conductivity . in various embodiments , the seal 1502 additional provides mechanical structure to the bobbin configuration , orienting the terminal 1516 with respect to the casing 1506 . various embodiments include a space 1504 which is empty . additional embodiments do not include space 1504 . some embodiments dispose a sealant in the space 1504 . additional embodiments dispose electrolyte in the space 1504 . various embodiments incorporate battery chemistries compatible with bobbin style configurations . embodiments within the present scope include , but are not limited to , at least one of a metal oxide , a metal sulfide , a metal selenide , a metal halide , a metal oxyhalide compound , and corresponding lithiated forms . some of these embodiments include at least one of manganese , vanadium , silver , molybdenum , tungsten , cobalt , nickel , chromium , and main group compounds such as carbon monofluoride and iodine . additionally , some embodiments include at least one of carbon , lithium , sodium , potassium , rubidium , cesium , magnesium , calcium , strontium , barium , tin , zinc or silver . primary battery chemistry embodiments fall within the present scope . additionally , secondary battery chemistry embodiments fall within the present scope . in some embodiments a power source of an implantable medical device includes a plurality of batteries connected in series , parallel or a combination of series and parallel . various electrode constructions fall within the present scope . embodiments compatible with bobbin construction are included , including monolithic electrodes , pelleted electrodes , and other electrodes which have a solid shape . pelleted electrodes , in various embodiments , include pellets formed from compressed powder , dough or slurry . some electrode embodiments are formed from a tightly wound ribbon which is wound unto itself without an insulator to separate progressive wraps from one another . additionally , some embodiment include an electrode onto which is pressed or coated an electronically conductive material . other electrode configuration embodiments compatible with bobbin batteries additionally fall within the present scope . additionally , various battery profiles using these electrodes fall within the present scope . embodiments with the present scope include , but are not limited to , batteries having a cylindrical shape , batteries having a prismatic shape , batteries having a button shape , and batteries having other shapes . in some examples , batteries have shape which is determined as a function of the shape &# 39 ; s impact on reducing blood flow . in some examples , batteries have shape which is determined as a function of the shape &# 39 ; s impact on reducing tissue damage during implantation . as such , various embodiments include an annular anode . some embodiments include an annular cathode . embodiments discussed herein demonstrate an annular cathode concentric with an annular anode . fig1 shows a cross section of a bobbin battery , according to one embodiment of the present subject matter . in various embodiments , a bobbin configuration includes a casing 1606 . in various embodiments , the bobbin configuration includes an anode 1608 . in various embodiments , the anode 1608 is interconnected with the casing 1606 . in various embodiments , the bobbin configuration includes a cathode 1610 . the cathode 1610 , in various embodiments , is connected to a terminal 1616 using a current collector 1612 . in various embodiments , a separator 1614 is disposed between the anode 1608 and the cathode 1610 . additionally , in various embodiments , a separator 1618 is disposed between the cathode 1610 and the casing 1606 . the polarity of components discussed herein is selected to assist in explanation , and can be reversed without departing from the present scope of embodiments . various embodiments require sealing the internal components of the bobbin configuration . in some of these embodiments , a seal 1602 is disposed between the terminal 1616 and the casing 1606 . in various embodiments , the seal 1602 resists electrical conductivity . in various embodiments , the seal 1602 additional provides mechanical structure to the bobbin configuration , orienting the terminal 1616 with respect to the casing 1606 . various embodiments include a space 1604 which is empty . additional embodiments do not include a space 1604 . some embodiments dispose a sealant in the space 1604 . additional embodiments dispose electrolyte in the space 1604 . this application is intended to cover adaptations or variations of the present subject matter . it is to be understood that the above description is intended to be illustrative , and not restrictive . the scope of the present subject matter should be determined with reference to the appended claims , along with the full scope of equivalents to which such claims are entitled .
an example includes apparatus including a non - thin - film battery , that can include an implantable housing , electronics disposed in the implantable housing , and a battery disposed in the implantable housing , the battery comprising : a plurality of cells electrically connected to one another , with at least one cell including a stack including at least one substantially planar anode having a thickness greater than 1 micrometer and at least one substantially planar cathode having a thickness greater than 1 micrometer , and a cell housing enclosing the stack of substantially planar anodes and cathodes and displacing less than approximately 0 . 024 cubic centimeters , wherein the plurality of cells are interconnected in at least one of series and parallel , and terminals interconnecting the battery and the electronics .