Haixian Pan

A Four-Channel Microelectronic System for Neural Signal Regeneration

A microelectronic system capable of recording from and stimulating spinal nerves at injury intervals after surgical implantation has been designed. As require of implantable engineering for the regeneration microelectronic system, the system is low noise, low power, small size and high performance. Such system, will be implanted in body for recording from and stimulating the spinal nerve and contribute for the function rebuilding of spinal nerve.

CMOS Microelectrode Array for Signal Recording and Stimulating of Neurons Assemble

a microelectrode array (MEA) chip for in-vitro signal recording and stimulating of neurons assemble is presented. The chip comprises 4×4 active sensor cells and ESD protection circuits. Each sensor cell is 60μm×60μm in dimension, including a 15μm×25μm stimulating electrode, a 15μm×25μm recording electrode and two NMOS switches which can linearly transfer signals with peak-to-peak values from 50 μV to 500 mV. The final chip is realized in a standard 0.5 μm DPDM (double-poly double-metal) CMOS technology. It covers an area of 1.0mm×1.0mm. The results of on-wafer electrical test indicate the independent electrical characteristic of the stimulating electrode and the recording electrode and verify the functionality of the NMOS switches. The tests carried out in the NaCl solution for the packaged chip have verified the electrical functionality of the MEA chip.

Design of neural stimulating and neural signal detecting circuit for monolithic integrated MEA

A neural stimulating circuit and a neural signal detecting circuit designed for a monolithic integrated MEA (micro-electrode array) are described. Two OPAs (operational amplifier) used as the basic cells of the circuits were designed. One is a telescopic OPA with low noise and low power, the other one is with rail-to-rail swing and constant gm. The circuits are realized in a standard 0.5-μm CMOS process (CSMC, Wuxi, China) and the test results of the circuits will be described.

Silicon-based microelectrode arrays for stimulation and signal recording of in vitro cultured neurons

Microelectrode arrays (MEAs) for stimulation and signal recording of in vitro cultured neurons are presented. Each MEA is composed of 60 independent electrodes with 59 working ones and one reference one. These electrodes are divided into 30 pairs. Through each pair of electrodes, four independent states can be realized to define the accessing modes of neurons cultured on the surface of the electrodes. A total MEA covers an area of 10 mm×10 mm. MEAs are fabricated in a silicon-based semiconductor process. An implemented MEA is bonded on a specially designed printed-circuit-board (PCB) and surrounded by a culture chamber. An impedance measurement has been made to verify the electrical characteristics of MEAs. The surface was modified to enhance the biocompatibility. A series of PC12 cells culture experiments validates the effectiveness of the modification. An extracellular signal recording experiment with acetylcholine (Ach) as a stimulant has been carried out, and the results show the feasibility of MEAs for extracellular action potential recording. Extracellular electrical stimulation and recording experiments have been carried out too. They indicate that MEAs can be used for extracellular stimulation, recording, simultaneous stimulation and recording, and isolation of PC12 cells network cultured in vitro.

Curve fitting of spikes in neural signals

Find an optimal function model of spikes of high signal-to-noise ratio (SNR) spontaneous signals in the spinal cord of a rat, and use it to recognize the patterns of spikes of low SNR signals in the sciatic nerve of the rat. Method: Firstly, several function models of spikes of high SNR spontaneous signals in the spinal cord of a rat are calculated under the rule of least square. By choosing an optimal function model based on minimum standard deviation (SD) of error of fitting, it is contrasted with the waveform of classical action potential (AP). Then, this model is used as a pattern to recognize spikes of low SNR signals in the sciatic nerve of the rat. Result: The optimal function model of spikes of high SNR spontaneous signals in the spinal cord of a rat is a proportional model whose numerator is a 5-order polynomial while the denominator is a 4-order polynomial. The waveform of a typical AP can be obtained from this model. It can also achieve good performance by recognizing the pattern of spikes of signals whose SNR is lower than 8 dB in sciatic nerve of the rat.