Made from semiconducting plastic, a low-cost sensor has the capability to monitor a wide range of health conditions, such as surgical complications or neurodegenerative diseases.
The sensor can read the amount of critical metabolites, such as lactate or glucose, in sweat, tears, saliva or blood. As part of a diagnostic device, it could allow health conditions to be monitored quickly, cheaply and accurately. That’s the word from a team led by the University of Cambridge and King Abdullah University of Science and Technology (KAUST) in Saudi Arabia that developed the sensor.
The new device is said to have a less complex design than existing sensors, and opens up a wide range of new possibilities for health monitoring down to the cellular level. The results are reported in the journal Science Advances. Up until now, semiconducting plastics such as those used in this sensor are being developed for use in solar cells and flexible electronics, but have not yet seen widespread use in biological applications.
“In our work, we’ve overcome many of the limitations of conventional electrochemical biosensors that incorporate enzymes as the sensing material,” said lead author Dr Anna-Maria Pappa, a postdoctoral researcher in Cambridge’s Department of Chemical Engineering and Biotechnology. “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.”
How did researchers build the new sensors? They used a newly-synthesized polymer developed at Imperial College that acts as a molecular wire, directly accepting the electrons produced during electrochemical reactions. When the material comes into contact with a liquid such as sweat, tears or blood, it absorbs ions and swells, becoming merged with the liquid. This leads to significantly higher sensitivity compared to traditional sensors made of metal electrodes.
The very first tests of the sensors were used to measure levels of lactate, which can be applied in fitness or to monitor patients following surgery. However, according to the researchers, the sensor can be easily modified to detect other metabolites, such as glucose or cholesterol by incorporating the appropriate enzyme, and the concentration range that the sensor can detect can be adjusted 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,” said Pappa. “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.”
The sensor is not composed of expensive materials like gold or platinum. Therefore, 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.
Something to think about: According to Pappa, some implantable device could be used 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.