Roland D. Rader

A monitoring technique providing quantitative rodent behavior analysis.

Abstract Behavior profiles of mice with different social roles can be monitored by dorsally or ventrally implanting small Alnico VIII magnets in the animal. The magnetically tagged mice trigger electronic checkpoints at colony nest boxes and a Hall Effect detector activates counting circuits, timers, and an event recorder. This new technique allows complete freedom of movement since there is no external hardware and permits behavioral analysis while the animal is socially interacting in a home environment.

An Implantable Blood Pressure and Flow Transmitter

A miniature totally implantable FM/FM telemetry system has been developed to simultaneously measure blood pressure and blood flow, thus providing an appreciation of the hemodynamics of the circulation to the entire body or to a particular organ. Developed for work with animal subjects, the telemetry systems transmission time is controlled by an RF signal that permits an operating life of several months.

An Interferometric Blood Flow Measurement Technique - A Brief Analysis

An ultrasonic interferometric technique of measuring blood flow with an extravascular probe is presented and analyzed. The difference in phase between pulses of ultrasonic energy transmitted simultaneously from a pair of barium titanate crystals diagonally through the vessel and received by the same pair of crystals is employed as the basic measurement of blood flow velocity. It is shown that the sensitivity is influenced mainly by variability in the internal diameter of the vessel and the zero-flow baseline voltage position is influenced principally by variations in the level of energy reflected from the vessel surfaces. Baseline stability is enhanced by the use of an asymmetrical probe which minimizes the variable reflection components. This measurement technique is currently being employed in long term telemetry implants in which flow measurements have been satisfactorily performed for periods in excess of three months duration.