Options for convenient monitoring of blood levels for alcohol and other addictive substances are somewhat limited. Engineers from the University of California San Diego have designed and completed preliminary in vitro tests for a tiny chip that can be injected under a person’s skin to monitor their blood alcohol level. It is powered and controlled wirelessly by a patch or smartwatch and they hope it will be a successful replacement for traditional methods such as breathalyzers and blood draws. Drew Hall, an electrical engineering professor who led the project, said:
The ultimate goal of this work is to develop a routine, unobtrusive alcohol and drug monitoring device for patients in substance abuse treatment programs. A tiny injectable sensor—that can be administered in a clinic without surgery—could make it easier for patients to follow a prescribed course of monitoring for extended periods of time.
The related paper describes the new device as a “wireless, fully-integrated injectable alcohol BioMote,” which was “designed for continuous, long-term monitoring.” The chip can be injected under the skin into the interstitial fluid, which surrounds the body’s cells. Once inserted, it is intended for ongoing use.
The biosensor contains an enzyme called oxidase that interacts with alcohol and creates a byproduct that is electrochemically detectable. It produces electrical signals that the paired wearable device detects. It is roughly one cubic millimeter and is designed to be ultra-low-powered. According to a UC San Diego press release, in order to function, it uses approximately 970 nanowatts, which is about 1 million times less than a smartphone uses to place a call. Its inventors aimed to reduce the heat the device creates within the body and avoid creating “a battery 
The first tests of these chips were conducted in vitro – inside test tubes or petri dishes, rather than a living organism. The experiment used mixtures of ethanol in diluted human serum, which is a portion of human blood plasma, under pig skin. Th engineers have now filed a provisional patent and live animal trials are in the works.
“This is a proof-of-concept platform technology. We’ve shown that this chip can work for alcohol,” Hall said, adding that his team hopes to apply the tech to other extended monitoring of “substances of abuse.”
It’s possible that questions of patient rights, privacy and data security may come up in regard to these chips, similarly to how they have been raised in relation to digital pills that track prescription adherence.
The paper, “A Sub-1 μW Multiparameter Injectable BioMote for Continuous Alcohol Monitoring,” was authored by Haowei Jiang and Xiahan Zhou, who contributed equally, Saurabh Kulkarni, Michael Uranian, Rajesh Seenivasan, and Drew A. Hall. It was presented at the 2018 IEEE Custom Integrated Circuits Conference in San Diego April 10.
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