Solution-gated thin-carbon-film field effect transistors for sensors and bioelectronics

In the Institute of Physics, Kazimierz Wielki University, we have undertaken a research project aimed at the construction of the SGFET sensors in which the conductive channel is made of different carbon materials. We consider both the sp3-bonded carbons such as diamond  as well as the sp2-bonded materials such as carbon nanotubes, graphene, graphene oxides. So far, we have been able to construct a pH sensor based on hydrogenated diamond film and bucky-paper containing single-walled carbon nanotubes.

Solution-gated field effect transistor (SGFET) is an electronic device with three electrodes (source, drain, and gate) and a thin conductive channel made of semiconductive material. The source is grounded while two different voltages are applied on the drain and the gate. Semiconducting layer and the gate are separated by the electrolyte instead of dielectric layer. By analogy to typical field effect transistors, the conductance of the semiconducting layer can be modulated by the gate voltage due to a change of the carrier concentration in the channel.

As the carrier concentration in the conduction channel changes under influence of the electroactive ions adsorbed on the semiconductor surface, SGFET is a promising devices for chemical and biological sensor in the detection of pH, Na+, K+, Ca2+, Mg2+, Pb2+ ions, biological analytes and bioreactions [Feng Yan, Meng Zhang, and Jinhua Li. Adv. Healthcare Mater. 2014, DOI: 10.1002/adhm.201300221]. Nowadays, the use of the SGFETs in bioelectronics is considered. The device could play a role of interface (neuro-prothesis) between the biological system, such as f. ex. retina in the eye, and standard microprocessors [Lucas H. Hess, Max Seifert, Jose A. Garrido. Proceedings of the IEEE. 2013, 101, 1780, DOI: 10.1109/JPROC.2013.2261031].

Many materials used as a conduction channel in SGFET are unstable in aqueous media that results in a decreased sensitivity in the surrounding tissue. In order to assure a high signal to noise ratio in SGFET transducers, chemically resistant materials are required which exhibit high charge carrier mobility. Carbon materials largely meet these expectations, are biocompatible and chemically stable in electrolytes. The problem we are working on is to determine the influence of (1)  the electronic structure of the sp3- and sp2-bonded carbons, (2) mobility of the electrons and holes, and (3) the structure of the electrolyte/conductive channel interface on the efficiency of the thin-carbon-film SGFET. We invite you to cooperation.

 


Contact: Paweł Szroeder, e-mail: psz@ukw.edu.pl

Institute of Physics, Kazimierz Wielki University