a modular ingestible capsule comprising a capsule body having an outer shell , a power supply , a transmitter connected with the power supply , an antenna connected with the transmitter , an activator configured to activate the power supply , and an electrical coupling element connected with the transmitter , a first modular sensing component configured and arranged to connect to the capsule body and having an outer shell configured and arranged to attach to the shell of the capsule body , a sensor for sensing a parameter of an ingestible tract , and an electrical coupling element connected with the sensor and configured and arranged to engage the electrical coupling element of the capsule body , whereby the first modular sensing component may be readily mechanically and electrically attached to the capsule body prior to ingestion of capsule by subject .