- Tiny biosensor chip injected beneath
the skin shown to be safe, convenient
and effective for continuous monitoring of alcohol levels of
patients in treatment programs
- Lack of effective and convenient
tools currently poses a major challenge to monitor patients in drug
injectable biosensor has been recently developed that works silently, constantly monitors alcohol levels in
patients. The sensor is powered wirelessly by a device such as a smart watch or
patch worn by the person.
biochip has been developed at UC San Diego
Jacobs School of Engineering
. The project was led by Professor Drew Hall
an electrical engineering professor at
the UC San Diego Jacobs School of Engineering who is also affiliated with the
Center for Wireless Communications and the Center for Wearable Sensors, both at
UC San Diego. The team present their work at the 2018 IEEE Custom Integrated
Circuits Conference (CICC) in San Diego.
Aim of Current Study
research team hope to develop a device
that overcomes the limitations of currently available tools
alcohol levels of patients in treatment programs.
‘Biochip that continuously monitors alcohol levels which are displayed on a smart watch worn by the patient could be an useful tool in rehabilitation programs.’
to Hall, "The ultimate goal of this work is to develop a routine,
unobtrusive alcohol and drug monitoring device for patients in substance abuse
Biosensor Chip and
Details of Study
research team initially tested the chip in vitro using a set-up that was
similar to an implanted environment, i.e., using mixtures of ethanol in diluted
human serum beneath layers of pig skin.
- The biosensor chip roughly measures
about one cubic millimeter in size and can be non-surgically injected
under the skin into the interstitial fluid (the fluid that surrounds the
- The sensor is coated with alcohol
oxidase, an enzyme that interacts selectively with alcohol to form a by-product
that can be electrochemically detected.
- The electrical signals from the chip
are sent wirelessly to a nearby wearable device on the skin such as a
smart watch, which powers the chip wirelessly as well.
- Two extra sensors on the chip
measure background signals and pH levels which are then canceled
out to make the test reading more accurate.
Limitations of Current
Tools to Monitor Alcohol Levels
of the main challenges for patients and doctors alike in treatment programs is
the lack of convenient tools to routinely monitor drug or alcohol levels.
- Breathalyzers are currently the most
common method to measure blood alcohol levels. However,
they are clunky devices and require to be switched on by the patient and
are not that accurate, says Dr Hall.
- A blood test is the most accurate
method, but has to be done by a trained technician.
- Tattoo-based alcohol sensors worn on
the skin are also a promising new
alternative, but can be easily removed and are only for one-time use.
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," Hall said.
Chip Safe and Consumes Very Little Power - An Added Advantage
- The team designed the chip to
consume very little power - 970 nano watts total, which is
approximately one million times less power than what a smartphone consumes
while making a phone call.
don't want the chip to have a significant impact on the battery life of the
wearable device. And since we're implanting this, we don't want a lot of heat
being locally generated inside the body or a battery that is potentially
toxic," Hall said.
was made possible by transmitting the signals via a phenomenon called backscattering
. In this method, the nearby device
such as a smart watch transmits radio frequency signals to the chip, which
sends the data back to the smart watch by modifying and reflecting the signals.
- The scientists also created
ultra-low power sensor readout circuits for the chip reducing its measurement
time to just three seconds, once again resulting in minimal power usage.
- The team is planning to test the
biochip in live animals
- Dr Hall's team is working with CARI
Therapeutics, a start-up based in the Qualcomm Institute Innovation Space
at UC San Diego, and Dr. Carla Marienfeld, an addiction specialist at UC
San Diego who specializes in managing persons with substance abuse
disorders, to optimize the chip for use as next generation rehabilitation
- The scientists are also actively
working to create versions of the chip that can be used to monitor other
drugs and substances of abuse as well in addition to alcohol.
To conclude with the remarks of Dr Hall,
"This is a proof-of-concept platform technology. We've shown that this
chip can work for alcohol, but we envision creating others that can detect
different substances of abuse and injecting a customized cocktail of them into
a patient to provide long-term, personalized medical monitoring."