[Image from the University of Cambridge]
The sensor is low-cost and measure the amount of critical metabolites, like lactate or glucose, that are in sweat, tears, saliva or blood. When the sensor is used with a diagnostic device, the researchers suggest it could be a quick, cheap and accurate way to monitor health conditions. So far, the device has a simpler design than other sensors and brings new potential to health monitoring on a cellular level, according to the researchers.
The University of Cambridge-developed device is comprised of semiconducting plastics that are similar to the ones that are currently being developed for solar cells and flexible electronics. However, those plastics have not seen widespread use in biological applications, yet.
“In our work, we’ve overcome many of the limitations of conventional electrochemical biosensors that incorporate enzymes as the sensing material,” Anna-Maria Pappa, the study’s lead author, said in a press release. “In conventional biosensors, the communication between the sensor’s electrode and the sensing material is not very efficient, so it’s been necessary to add molecular wires to facilitate and ‘boost’ the signal.”
Pappa and her team of researcher built the sensor using a newly-synthesized polymer that was developed at Imperial College. The polymer acts like a molecular wire and directly accepts the electrons that are produced during electrochemical reactions. Once the material comes into contact with a liquid like sweat, blood or tears, it can absorb the ions and begins to swell and become merged with the liquid. When it merges with the liquid, there is higher sensitivity compared to traditional sensors made from metal electrodes.
Once the sensors are used in more complex circuits like transistors, the signal is amplified and can respond to tiny changes in metabolite concentration, even though the device itself is small.
The sensors were originally tested to measure levels of lactate, a measurement that is useful for fitness applications and monitoring patients post-surgery. The researchers say that the sensor can easily be modified to detect other important metabolites like glucose and cholesterol by changing the device’s geometry.
“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, which allows for the direct detection of a metabolite: this hasn’t been straightforward until now,” Pappa said. “It opens up new directions in bio sensing, where materials can be designed to interact with a specific metabolite, resulting in far more sensitive and selective sensors.”
Since the sensor is made from plastic and not metals like gold and platinum, it can be manufactured for a low cost and can easily be integrated into flexible and stretchable substrates, enabling the sensor to be used in wearable or implantable sensing applications.
“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 seizure or to assess treatment,” Pappa said.
The researchers plan to develop the sensor to monitor metabolic activity in human cells in real-time outside of the body.
The research was published in the journal Science Advances and was funded by the Marie Curie Foundation, the KAUST Office of Sponsored Research and the Engineering and Physical Sciences Research Council.
