Introduction

Electrocorticography (ECOG) and micro-electrocorticography (mECOG) are widely used non-invasive techniques to record bioelectrical signals in the brain. They are  less invasive than intracortical devices, although they suffer for spatial resolution limitation and noise, due to the greater distance at which measurements are carried out. Clinically there is a need for bioelectrical brain signal detection techniques, that are minimally invasive, reliable and with high spatio-temporal resolution. This is where transistor technologies come in. Organic Electrolytic Transistors were demonstrated to overcome the limitations inherent to ECOG devices, however, when these are used as amplifiers there is a risk of causing critical tissue damage in in vivo applications because of parasitic electrochemical reactions.

Technical features

A method to produce a biosensor for the transduction of bioelectrical signals and to amplify a bioelectrical/biochemical signal, has been developed, that overcomes the drawback of established recording techniques. The device presented is composed of a source measure unit having two-channels, each with a high and low terminal, respectively and an EGOT (Electrolyte-Gated Organic Transistor), made on a thin film of semiconductive/conductive organic material designed to contact an electrolyte equipped with a source electrode and a drain electrode. Both electrodes are interconnected by the thin film, and a gate electrode has been designed to contact the electrolyte. By means of altering the positive or negative voltage to the drain electrode, with respect to the grounded source electrode, the inventors have been able to amplify the electrical signal without any repercussion in in vivo applications, specifically avoiding any parasitic faradic current that can be harmful.

Possible Applications

• Detection of bioelectrical signals in the brain;
• Label-free biosensor applications in the brain.

Advantages

• Detection of bioelectrical signals whilst minimizing the invasiveness;
• Providing in situ amplification of the first stage signal;
• No current will be injected in the brain, ensuring safety of the tissue;
• Ability to obtain clean, uniquely interpretable signals.