There are various conditions that can cause muscle twitching. Minor muscle twitching is usually the result of less serious, lifestyle-related causes. More severe muscle twitching, however, is often the result of a serious condition.
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or air).
Background -- Ion Selective Electrodes (ISE) are membrane electrodes that respond selectively to ions in the presence of others. These include probes that measure specific ions and gases in solution. The most commonly used ISE is the pH probe.