A Few Final Notes

The series resistance of a glass microelectrode is generally quite high. If isotonic saline solution (0.1 5n) is used as the electrolyte, a typical glass electrode will exhibit a series resistance of the order of 1000 MQ. Such a resistance would cause too high a voltage drop with respect to the usual input impedance values of microelectrode preamplifiers (see Chapter 7 on preamplifiers). For this reason, 2 or 3n KCl solution is used to fill the electrode lumen. This results in an electrode series resistance of 50 to 100 MQ. 

Generally, metal microelectrodes are useful for stimulation, or for recording high-frequency processes. Glass electrodes are useful in recording from cells in which membrane processes are of interest. Unfortunately, there is no general-purpose microelectrode. Preamplifiers will be discussed in subsequent chapters, as other aspects of microelectrode use are considered. 

---

A few final notes on your accident review committee ... 

---