Organic Electrochemical Sensor Detects Metabolites Directly

Low-cost sensors made from semiconducting plastic could be used to diagnose and monitor a wide range of health conditions, claims a new study.

Developed at King Abdullah University of Science and Technology (KAUST; Thuwal, Kingdom of Saudi Arabia), Centre Microélectronique de Provence (CMP; Gardanne, France), and other institutions, the novel sensor is based on the ion-to-electron transducing qualities of an electron-transporting (n-type) all-polymer organic semiconductor, which incorporates hydrophilic side chains to enhance ion transport/injection, as well as to facilitate enzyme conjugation.

The micrometer-scale platform absorbs ions produced during enzymatic reactions, causing it to swell when in contact with body liquids such as sweat, tears, or blood. The result is a selective, sensitive, and fast metabolite sensor. When the sensors are merged into more complex circuits, such as transistors, the signal can be amplified and respond to tiny fluctuations in metabolite concentration, leading to significantly higher sensitivity compared to traditional sensors made of metal electrodes, and without the need for a reference electrode.

Initial tests of the sensors were used to measure levels of lactate, a significant metabolite in cellular metabolic pathways associated with several critical health care conditions. According to the researchers, the sensor can also be easily modified to detect other major metabolites, such as glucose or cholesterol, by incorporating the appropriate enzymes into the platform, with the possible concentration range that the sensor can detect adjusted by changing device geometry. The study was published on June 22, 2018, in Science Advances.

“This is the first time that it's been possible to use an electron accepting polymer that can be tailored to improve communication with the enzymes. It opens up new directions in biosensing, where materials can be designed to interact with a specific metabolite, resulting in far more sensitive and selective sensors,” said lead author chemical engineer Anna Maria Pappa, PhD, of CMP. “An implantable device could allow us to monitor the metabolic activity of the brain in real time under stress conditions, such as during or immediately before a seizure, and could be used to predict seizures or to assess treatment.”

Since the sensor does not consist of metals such as gold or platinum, it can be manufactured at a lower cost and can be easily incorporated in flexible and stretchable substrates, enabling their implementation in wearable or implantable sensing applications.

Related Links:
King Abdullah University of Science and Technology
Centre Microélectronique de Provence