Listening to neurons - development and understanding of microelectrode arrays (MEA's) systems

QH301 Biology;TK Electrical engineering. Electronics Nuclear engineering

Tang, Rongyu ; Wilkinson, Chris

University:University of Glasgow

Department:School of Engineering

关键词: MEA, pMEA, FlexMEA, Microelectrodes, 'neural bathtub', neural network, Jude pattern, Action potential, Extracelluar recording;   

Others  :  http://theses.gla.ac.uk/778/1/2009tangphd.pdf

来源: University of Glasgow

【 摘 要 】

This thesis is about the development of microelectrodes array system (MEAs), the simulation of the neuron and the recording to the living neural network. We cultured the nerve cells of rat inside a container called 'neural bathtub' and guided them to form predetermined network (Jude pattern) with topographical features or protein traces. In order to record the electrical activity of these nerve cells, two types of MEA systems (FlexMEAs and pMEAs) were designed and built. These extracellular MEA systems were aimed to form one-electrode-to-one-neuron connection with neural network. To assist the design, many models were built, e. g. the impedance model of the microelectrode/electrolyte interface, the oxygen model inside the 'neural bathtub'.During this project many difficulties were encountered especially at the coupling of MEA to neurons. To explore these questions more models and simulations were included into this thesis. The excitable membrane of neuron and the interface of neuron to microelectrode are modelled and investigated. These simulations help to explain many questions, e.g. how to form a good coupling of neuron/electrode, how the waveform of extracellular spikes changes and how much power is dissipated when neuron generates an action potential. The first chapter introduces this project, the history of MEA and some biology about neuron. The fabrication processes of devices (the MEAs, the 'bathtub', the mould of Jude pattern and the preamplifier) are described in the second chapter. Chapter 3 gives the detail of the designs of these devices and how they were evolved and optimised. Chapter 4 is about the impedance model of the microelectrode, the measurements of the impedance and the data fitting to obtain the parameters of the model. Chapter 5 models the oxygen concentration inside the 'neural bathtub'. The simulation tells whether the diffusion provides enough oxygen to sustain the nerve cells. It helped us to modify the design of 'neural bathtub'. Chapter 6 introduces the basic principle of different microelectrode system from a circuit perspective. The importance of the seal resistance to the coupling of neuron/electrode is investigated using a circuit model. The noise caused by the preamplifier itself is estimated also. Chapter 6 also introduces a model based on the classical model by Hodgkin and Huxley (1952). The differences between the waveforms of the extracellular potential are explored with the help of the model in this chapter. Chapter 7 represents the signal recorded from different cells with different setups. The signal is analysed preliminarily.