There is a big need for electronic biosensors that can be operated in water for biomedical applications and environmental monitoring. Devices based on organic materials are currently attracting great attention for applications where low-cost, large area coverage and flexibility are required. Water is an aggressive medium and due to its chemical activity the operational voltage window for stable sensor operation is limited. Related to that, in the past, degradation under both ambient and aqueous environments have limited their application in bio sensors for portable, label-free detection in the field of healthcare and environmental monitoring.
Quite recently, our group has demonstrated stable FET device operation based on organic active materials directly exposed to water and more interestingly, even sea water.[1-3] By pattering an array of gold nano-particles on top of the organic semiconductor but close to the transistor channel, the developed structure was able to sense low concentrations of mercury ions in sea water.[2,3]
Here we would like to present the second generation of this highly sensitive bio-sensor platform based on organic field-effect transistors developed in our group able to operate at even lower voltages which is a necessary condition for stable device operation in water based environments.[4,5] Functionalization is a powerful tool to attach receptor units close to the transistor channel which are able to detect its corresponding analytes. This methodology allows preparing a scalable, easy producible and high performing sensor platform suitable for portable biosensing in aqueous media.
 M. E. Roberts et. al., PNAS, 105, 12134 –12139, 2008.
 M. L. Hammock et al., ACSNano, 6, 3100-3108, 2012.
 O. Knopfmacher et. al. Nature Communications, 5, 2954, 2014.
 C. Wang, et al. Scientific Reports, 5, 17849, 2015.
 D. Kong, et al. Advanced Functional Materials, 26, 4680–4686, 2016.