Temporal Dynamics of Transdermal Alcohol Concentration Measured via New-Generation Wrist-Worn Biosensor

Abstract

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.

Keywords: Alcohol; Biosensor; Blood Alcohol Concentration; Measurement; Transdermal.

Figure 1.

AMS SCRAM ankle bracelet (left) and BACtrack Skyn wrist monitor (right) displayed side-by side. The top panel displays these devices as worn on ankle/wrist, whereas the bottom panel displays them to scale. The approximate weight of the devices is 6oz (SCRAM) and 1oz (Skyn prototype), respectively.

Figure 2.

Skyn prototype, SCRAM, and BrAC data for each of the 25 participants assigned to receive alcohol (P1-P25) as well as the 5 no-alcohol control participants (P26-P30). Data reflects the entire period of assessment, beginning from the moment just prior to first alcohol consumption (beginning of the drink period) to the final BrAC reading. For this visualization of Skyn data, data was standardized by subtracting the lowest value for each participant file, and a 30-minute moving average window was also applied.