Temporal Dynamics of Transdermal Alcohol Concentration Measured via New-Generation Wrist-Worn Biosensor.
BACKGROUND
The development of a transdermal alcohol biosensor could represent a tremendous advance toward curbing problematic drinking. But several factors limit the usefulness of extant transdermal technology, including relatively lengthy delays between blood alcohol concentration (BAC) and transdermal alcohol concentration (TAC), as well as the large/bulky designs of currently available transdermal sensors (e.g., ankle monitors). The current research examined the lag time between BAC and TAC using a prototype of BACtrack Skyn-a new-generation wrist-worn transdermal sensor featuring a compact design and smartphone integration.


METHODS
Participants (N = 30) received either a dose of alcohol (target BAC 0.08%) or a nonalcoholic beverage in the laboratory while wearing both the AMS SCRAM ankle monitor and a Skyn prototype. Participants were monitored in the laboratory until breath alcohol concentration (BrAC) dropped below 0.025%.


RESULTS
Device failure rates for Skyn prototypes were relatively high (18 to 38%) compared with nonprototype SCRAM devices (2%). Among participants with usable data, both Skyn- and SCRAM-measured TAC showed strong correlations with BrAC, and both Skyn and SCRAM devices detected alcohol within 30 minutes of first alcohol administration. Skyn-measured TAC peaked over 1 hour earlier than SCRAM-measured TAC (54 versus 120 minutes after peak BrAC, respectively), and time-series models suggested that, on average across all measured portions of the BrAC curve, Skyn TAC lagged behind BrAC by 24 minutes, whereas SCRAM TAC lagged behind BrAC by 69 minutes-all differences statistically significant at p < 0.001.


CONCLUSIONS
Results provide preliminary evidence for the validity of a new-generation wrist-worn transdermal sensor under controlled laboratory conditions and further suggest favorable properties of this sensor as they pertain to the latency of transdermal alcohol detection. The prototype version of Skyn employed here displayed a higher failure rate compared with SCRAM, and, in future, more reliable and robust Skyn prototypes will be required suitable to field testing across diverse environmental conditions.