Patients may stay on top of their medications thanks to a tiny, touch-based sensor

Patients may stay on top of their medications thanks to a tiny, touch-based sensor ...

Credit: Jialun Zhu and Shuyu Lin A tiny touch-based sensor measures lithium concentrations in the body.

lithium can reduce symptoms of bipolar disorder and depression in just the right dosage. Too little will not help, while too much might lead to serious side effects. Today, researchers report the discovery of a tiny sensor that detects lithium levels from sweat on the surface of a fingertip in as little as 30 seconds.

The researchers presented their findings last week at the American Chemical Society's fall meeting. ACS Fall 2022 featured around 11,000 presentations on a wide spectrum of science topics.

Lithium must be taken at a specific dosage, and patients may not be able to take it as prescribed, and may miss pills. These disadvantages exist because to the fact that current methods of monitoring are invasive and time-consuming. Pill counters, however, cannot accurately measure the dosage of the medication.

Shuyu Lin, Ph.D., is a postgraduate student researcher who co-presented the research with Jialun Zhu, a graduate student. "We saw this as an opportunity to develop a new kind of sensor that would detect these substances."

Our new device can provide clinically relevant molecular-level information about what is happening in the body via a single touch, according to Sam Emaminejad, the principal investigator at the University of California, Los Angeles (UCLA). “We already interact with a lot of touch-based devices, such as smartphones and keyboards, so this sensor might seamlessly integrate into everyday life.”)

However, constructing a lithium sensor provided some technical difficulties. Sweat is typically only present in small amounts, but the electrochemical detection needed to detect charged lithium particles required an aqueous, or watery, environment. The scientists created a water-based gel containing glycerol, which prevented the gel from drying out and created a controlled environment for the electronic portion of the sensor.

The researchers used an ion-selective electrode to trap lithium ions as they entered the gel. This difference in electrical potential allowed the researchers to estimate the quantity of lithium present in sweat in around 30 seconds.

The researchers recruited real individuals to test the sensor, including one person on a lithium therapy regimen. They discovered that these measurements were comparable to those measured by saliva, which prior research has demonstrated to accurately measure lithium levels. In the future, the researchers will investigate the effects of lotion and other skin products on the sensor's readings.

Emaminejad is developing touch-based sensors to measure alcohol and acetaminophen, a painkiller known by the brand name Tylenol®, as well as exploring the possibility of discovering other substances. For substances that are often misused, a robotic dispensing system that administers medication only when the patient has a low level in their bloodstream.

The research group receives funding from the National Science Foundation, the Brain and Behavior Foundation, Precise Advanced Technologies and Health Systems for Underserved Populations, and the UCLA Henry Samueli School of Engineering and Applied Sciences.

Title Non-invasive lithium monitoring using an organohydrogel-based sensing interface through Touch-based Touch-based

Abstract For individuals with bipolar disorder, the narrow therapeutic window ( 0.6 – 1.2 mM) and high nonadherence rate ( 40%) make lithium a must-have treatment therapy. Moreover, current indirect monitoring methods (e.g. pill counters) are ineffective of verifying the actual intake event (inherently non-specific).

Here, we describe a touch-based non-invasive lithium monitoring technique for decentralized lithium pharmacotherapy management. The hydrogel-coated electrode (TOH-ISE) was developed to provide stable water flow for > 2 weeks storage in an ambient environment, fulfilling a key requirement for real-life lithium monitoring.

The developed touch-based sensing interface was successfully tested on a patient receiving lithium-based medicine, where the decrease in the circulating drug levels after the dosage was verified. Collectively, our preliminary findings demonstrate the suitability of our touch-based solution for lithium adherence monitoring, and more broadly for managing lithium-based pharmacotherapy.

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