An accurate, long-term, pH-sensitive radio pill for ingestion and implantation

The design of a new radiotelemetry capsule (26 mm long X 7.6 mm diameter), with an in vivo life of 1 month is described in the context of previous work in this field. In vitro evaluation of the capsule indicates an accuracy and performance comparable with a conventional pH meter. Several clinical applications are described, including measurements of gastrointestinal pH in humans and the measurement of extracellular pH in laboratory animals.