Wrist-worn alcohol biosensors: Strengths, limitations, and future directions

Abstract

Wearable alcohol biosensors have emerged as a valuable tool for noninvasive, objective, and continuous monitoring of alcohol consumption. However, to date their research and clinical applications have been limited by several factors including large size, high cost, and social stigma. In contrast, recently developed wrist-worn alcohol biosensors are smaller, less expensive, and may be more acceptable for daily use. However, these devices are at the prototype phase and have just begun to be tested for research applications. In this paper, we describe our experiences with two prototypes of these new wrist-worn alcohol biosensors (i.e., Quantac Tally and BACtrack Skyn) and their associated smartphone applications in both a controlled laboratory setting and the real-world environment. Our preliminary experiences with these devices highlight their advantages including comfort, high participant acceptability, and good compliance. However, there are various limitations that should be addressed prior to future research applications of these biosensors, including large interpersonal variations in transdermal alcohol readings, lack of immediately applicable data analysis/interpretation software, and poor battery life after a few months. More research is also needed to further validate the new biosensors, and investigate individual (e.g., skin thickness, gender differences) and environmental factors (e.g., humidity, temperature) contributing to the variations in transdermal alcohol readings measured by wrist-worn alcohol biosensors.

Keywords: Behavioral monitoring; Heavy drinking; Transdermal alcohol sensor; Wearable alcohol biosensor.

Conflict of interest statement

Conflict of interests

None to declare.

Copyright © 2018 Elsevier Inc. All rights reserved.

Figures

Figure 1.

Visual comparison of SCRAM CAM, Quantac Tally and BACtrack Skyn devices Note. The pictures of the wrist-worn devices were prototypes we obtained for testing as of early 2018. We placed a coin (i.e., a quarter) in the Top view picture as a reference for the actual size of these new wrist biosensors.

Figure 2.

User interface of Quantac Tally and BACtrack Skyn Note. The screenshot on the left is from the Quantac Tally app. The one on the right is from the BACtrack Skyn app. These two screenshots were taken in different drinking episodes when one of the authors was testing these devices.

Figure 3.

Example of BrAC and alcohol biosensor data recorded from a 24-year-old male participant using a Quantac Tally device during a laboratory alcohol challenge (alcohol dose = 0.8g/kg).

Figure 4.

Example of BrAC and alcohol biosensor data recorded from a 23-year-old female participant using a BACtrack Skyn device during a laboratory alcohol challenge (alcohol dose = 0.8g/kg).

Figure 5.

Example of real-world data recorded from a 34-year-old female participant using a Quantac Tally device during a 16-hour field test Note. The drinking episode started around 6pm with significant elevation in TAC, followed by a peak at 9pm, and slow decline over time. The pilot participant indicated in the app that she consumed 1.5 standard drinks (wine) around 6pm. At 5pm, there was a notable spike of TAC readings that was likely to be an environmental alcohol exposure, as the slopes were too steep to reflect human alcohol metabolism. This type of spike would be identified as a non-drinking event in post processing by applying criteria such as those in the TASMAC Macro. Note that the signal dropout visible in the alcohol sensor channel around 9pm corresponds to rapid and transient change in temperature and humidity. This may indicate a period where the biosensor was removed and reapplied. It is also worth noting that there were significant fluctuations in TAC after 9pm, although these fluctuations may be common in these new wrist biosensor prototypes (also see Figure 2, 3).