Chapter 16 Microelectrode electronics

These notes are intended to provide an introduction to the electronics of microelectrode and patch clamp amplifiers. How much electronics do you need to use a physiological amplifier? Enough to know how much distortion is introduced by the measurement. This means (1) testing the response to an input that simulates the physiological signal, (2) calibrating the gain and frequency response, and (3) knowing the errors that might arise from limited performance. This ‘black box’ approach to instruments is the minimum needed and requires a knowledge of the basic principles of electronic circuits. It is fine until something goes wrong or a special requirement arises which prompts a look inside to see how things work and whether a modification can be made. It is worthwhile taking a practical course in e.g. medical electronics if one is available and working in the electronics workshop for a period to learn soldering from an expert. For those interested in making circuits, applications are given below of operational amplifiers in circuits which may be useful for signal processing and can be built relatively easily and cheaply. Building operational amplifier circuits is a very good way of learning the basics of electronics the amplifiers commonly used are inexpensive enough to permit a degree of trial and error and standard printed circuit boards are available. A knowledge of the properties and jargon of low-pass filters is necessary for survival. These are introduced and their use prior to digitizing data for computer analysis is discussed. Many topics have not been included and for these, and wider coverage of topics introduced here, a list of books and articles for further reading and reference is appended.