A CMOS INTEGRATED-CIRCUIT FOR MULTICHANNEL MULTIPLE-SUBJECT BIOTELEMETRY USING BIDIRECTIONAL OPTICAL TRANSMISSIONS

A CMOS integrated circuit for a noninvasive biological-signal telemetr y system specified for use in medical and physiological studies of the influence of weightlessness in space is presented. The system can mon itor multichannel (4 channels maximum) biological signals from multipl e subjects (4 subjects maximum) in real time by using time multiplexin g. A key technique, so-called synchronized multiple-subject telemetry, to achieve multiple-subject telemetry has been proposed. This techniq ue utilizes bidirectional optical transmissions with direct and scatte red infrared lights between an observer and each of the subjects. An e xperimental CMOS IC to give a small light-weight low-power, and smart telemetry instrument for use on animals has been developed. This IC is for evaluating circuit blocks of the implantable monolithic telemetry instrument. The major circuit blocks include CMOS digital circuits fo r synchronization, subject selection and time multiplexing, analog cir cuits for pulse interval modulation (PIM), and other blocks such as a CMOS optical pulse receiver and an LED driver. A preliminary experimen tal multichannel telemetry from two subjects has been performed with t he implemented IC chips, and the principal operation of the multiple-s ubject optical biotelemetry has been demonstrated.