docs: def get_viscosity(medium="CellCarrier", channel_width=20.0, flow_rate=0.16,
                    temperature=23.0):
      """Returns the viscosity for RT-DC-specific media
  
      Parameters
      ----------
      medium: str
          The medium to compute the viscosity for.
          One of ["CellCarrier", "CellCarrier B", "water"].
      channel_width: float
          The channel width in µm
      flow_rate: float
          Flow rate in µl/s
      temperature: float or ndarray
          Temperature in °C
  
      Returns
      -------
      viscosity: float or ndarray
          Viscosity in mPa*s
  
      Notes
      -----
      - CellCarrier and CellCarrier B media are optimized for
        RT-DC measurements.
      - Values for the viscosity of water are computed using
        equation (15) from :cite:`Kestin_1978`.
      """
      if medium.lower() not in ["cellcarrier", "cellcarrier b", "water"]:
          raise ValueError("Invalid medium: {}".format(medium))
  
      # convert flow_rate from µl/s to m³/s
      # convert channel_width from µm to m
      term1 = 1.1856 * 6 * flow_rate * 1e-9 / (channel_width * 1e-6)**3 * 2 / 3
  
      if medium == "CellCarrier":
          temp_corr = (temperature / 23.2)**-0.866
          term2 = 0.6771 / 0.5928 + 0.2121 / (0.5928 * 0.677)
          eta = 0.179 * (term1 * term2)**(0.677 - 1) * temp_corr * 1e3
      elif medium == "CellCarrier B":
          temp_corr = (temperature / 23.6)**-0.866
          term2 = 0.6771 / 0.5928 + 0.2121 / (0.5928 * 0.634)
          eta = 0.360 * (term1 * term2)**(0.634 - 1) * temp_corr * 1e3
      elif medium == "water":
          # see equation (15) in Kestin et al, J. Phys. Chem. 7(3) 1978
          if np.min(temperature) < 0 or np.max(temperature) > 40:
              msg = "For water, the temperature must be in [0, 40] degC! " \
                    "Got min/max values of '{}'.".format(np.min(temperature),
                                                         np.max(temperature))
              raise ValueError(msg)
          eta0 = 1.002  # [mPa]
          right = (20-temperature) / (temperature + 96) \
              * (+ 1.2364
                 - 1.37e-3 * (20 - temperature)
                 + 5.7e-6 * (20 - temperature)**2
                 )
          eta = eta0 * 10**right
      return eta