AN INSTRUMENT TO CONTROL AN ARRAY OF 12 ION-SELECTIVE FIELD-EFFECT TRANSISTORS

A computer-based instrument has been constructed which controls six in tegrated circuits containing twelve ion-selective field-effect transis tors, and another twelve insulated-gate field-effect transistors used as controls. Each sensor is individually controlled and all the output s are monitored simultaneously. The instrument is operated by a combin ation of digital input/output, analog-to-digital, and digital-to-analo g conversion from a microcomputer equipped with a commercial data-acqu isition board running under the Asyst software package.