Versatile digital data logger: storage of gastrointestinal motility data

Abstract

An inexpensive four-channel data logger for recording gastrointestinal potentials is described. A 512 K bytes memory and a sampling speed of 1·25 Hz per channel is adequate for these potentials and permits recordings for up to 27 hours. The small size and light weight allow the device to be carried in a pocket so that recordings can be made while the subject is freely ambulatory. A separate replay unit allows the data stored in the data logger to be presented to a chart recorder or to an interface card in a PC AT. This interface, a Microsoft C vers 5.0 program and the computer display the data as single frames or scrolled, expanded or condensed on either the time or amplitude axis. From the computer the data can be written to a printer and displayed as a chart or to an ASCII format file which can be used for analysis with statistical packages. Examples of recordings from both man and dog are illustrated and the analogue recorded data are compared with data digitally recorded. It is suggested that the data logger has many applications where long-term slow potential changes must be recorded under specially difficult conditions.