Keynote Address: Principles and applications of biotelemetry

Biotelemetry provides a means for monitoring and studying human and animal physiologic functions from a remote site with the goals of minimally encumbering or disturbing normal activity allowing ambulatory freedom and often to place the investigator out of harm''s way. Since the early 1950''s biotelemetry has been applied to a wide variety of subjects ranging in size from bees to whales over distances from several feet to thousands of miles. The evolution in sophistication miniaturization and reliability has paralleled the improvements of electronic components and assembly capabilities available to investigators. Modern biotelemetry began as a single transistor Endoradiosonde but now is found in sophisticated miniaturized microcontroller implementations. Signals derived from physiologic transducers have been encoded and formatted in many different ways in an effort to improve transmission reliability and carrier signals have included radio sound and light in air space and water. Power sources have been developed using both primary and secondary cells. Power can now be transferred at radio frequency across the tissues to implanted biotelemeters and their rechargeable batteries to provide for long operational lifetimes. The field of biotelemetry is truly exciting challenging and diverse in new circuit realizations and applications to living subjects.