The necessity for quick, reliable, easy-access and low-cost devices for healthcare assessment is currently attracting a great deal of interest and the market for such products is growing rapidly. This contribution deals with a novel class of Point-of-Care devices based on poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) Organic Electrochemical Transistors (OECTs).

OECTs are promising electronic platforms that have recently attracted increasing interest, since they can provide intrinsic signal amplification without the need of a freestanding reference electrode, they can operate at low power (< 100 μW) and can be easily miniaturized and adapted to non-flat, flexible and even textile substrates. In addition, providing high sensitivity together with biocompatibility and low-cost, could be proposed as analytical tools for the reliable detection of a wide range of low concentration analytes even in biological fluids.

All PEDOT:PSS OECTs can be used as chemical sensor for the detection of redox analytes able to undergo oxidation at PEDOT:PSS, such as ascorbic acid, dopamine, adrenaline or uric acid. The redox molecules react with PEDOT:PSS by extracting charge carriers from the transistor channel, and consequently an increase of analyte concentration leads to a decrease of the absolute value of the drain current that is used as the analytical signal[1].

On the other hand, the selectivity issue must be addressed to allow the widespread use in real-life applications, through a proper functionalization of the gate electrode with molecules able to selectivity interact with the target analyte [2]. In this regard glucose and lactate biosensors have been fabricated by immobilizing the enzyme glucose oxidase or lactate oxidase on the gate surface; moreover pH or chloride sensors have been described, entrapping iridium oxide or silver/silver-chloride nanoparticles on the PEDOT polymer, thus developing a two terminal sensor able to work without an external gate electrode.

As an example of application, a smart bandage has been realized for the real-time monitoring of wound pH, which has been reported to correlate with the healing stages, thus potentially giving direct access to the wound status without disturbing the wound bed. The fully textile device is realized by integrating a sensing layer, including the two-terminal pH sensor made of a semiconducting polymer and iridium oxide particles, and an absorbent layer ensuring the delivery of a continuous wound exudate flow across the sensor area[3].