Health In Focus
  • 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 rehabilitation programs

New 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.

The 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

The research team hope to develop a device that overcomes the limitations of currently available tools to monitor alcohol levels of patients in treatment programs.
Injectable Biosensor To Monitor Alcohol Levels Longterm

According to Hall, "The ultimate goal of this work is to develop a routine, unobtrusive alcohol and drug monitoring device for patients in substance abuse treatment programs."

Biosensor Chip and Details of Study

The 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 cells).
  • 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

One 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.
"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," Hall said.

Biosensor 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.
"We 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.

This 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.

Future Plans

  • 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 monitoring.
  • 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."

Source: Medindia

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