An organic transistor matrix for multipoint intracellular action potential recording

Electrode arrays are widely used for multipoint recording of electrophysiological activities, and organic electronics have been utilized to achieve both high performance and biocompatibility. However, extracellular electrode arrays record the field potential instead of the membrane potential itself, resulting in the loss of information and signal amplitude. Although much effort has been dedicated to developing intracellular access methods, their three-dimensional structures and advanced protocols prohibited implementation with organic electronics. Here, we show an organic electrochemical transistor (OECT) matrix for the intracellular action potential recording. The driving voltage of sensor matrix simultaneously causes electroporation so that intracellular action potentials are recorded with simple equipment. The amplitude of the recorded peaks was larger than that of an extracellular field potential recording, and it was further enhanced by tuning the driving voltage and geometry of OECTs. The capability of miniaturization and multiplexed recording was demonstrated through a 4 × 4 action potential mapping using a matrix of 5- × 5-μm2 OECTs. Those features are realized using a mild fabrication process and a simple circuit without limiting the potential applications of functional organic electronics.

New Advances in Single Fiber Electromyography

The aim of this chapter is to present a general perspective of SFEMG together with a description of the anatomical, physiological, and technical aspects that are involved in the recording of single fibre action potentials (SFAPs). First, a simulation model that relates analytically the intracellular action potential (IAP) and SFAP mathematical expressions is described. Second, the most recent findings regarding the shape features of human SFAPs are outlined. Third, a description of how different types of needle electrodes affect the characteristics of the recorded potential is detailed. Fourth, an explanation of the most important effects of filtering on the SFAP characteristics is provided. Finally, a description of the principles of jitter estimation together with the most important sources of errors is presented.