Nanoscale Field-Effect Transistors for Minimally Invasive, High Spatial Resolution, and Three-Dimensional Action Potential Recording [chapter]

Xiaojie Duan
2014 Nanotechnology and Neuroscience: Nano-electronic, Photonic and Mechanical Neuronal Interfacing  
This chapter is devoted to the development and application of nanoscale fi eld-effect transistors (FETs) for neural and cardiac activity recording. Compared to optical methods, the electrical recording of action potentials has high signal-to-noise ratio (SNR) and temporal resolution. But the need for electrodes limits its spatial resolution and also poses perturbation on the biological system under investigation. One way to overcome these problems is to develop electrical recording devices with
more » ... nanometer size and high-density scaling-up ability. Microfabricated metal electrodes can be readily patterned into arrays, but it is hard to decrease the size of these electrodes to nanometer scale because of the necessity to ensure a reasonable impedance value at the electrode/electrolyte interface for suffi cient SNR. Field-effect transistors (FETs), on the other side, can sense the potential of the solution independently on the device/electrolyte interface impedance and hence allow for the miniaturization of the probes to nanometer scale, which is important for minimally invasive, high spatial resolution electrical recording and mapping of neuronal activities, as will be discussed in this chapter. In a standard FET, the conductance of the semiconductor channel between the source ( S ) and ( D ) drain electrodes is modulated by a third gate ( G ) electrode capacitively coupled through a thin dielectric layer to the semiconductor. In the case of a p-type semiconductor, applying a positive gate voltage depletes majority of charge carriers (positive holes) and reduces the conductance, whereas applying a negative gate voltage leads to an accumulation of carriers and a corresponding increase in conductance ( Fig. 2.1 ) [ 1 , 2 ]. If the FET is immersed into an electrolyte solution, the solution can act as analog of metallic gate electrode in the conventional FET
doi:10.1007/978-1-4899-8038-0_2 fatcat:7o2xw7azvbavhlsywxzejtvuci