Research Area: Implantable Devices Robert G. Dennis, Ph.D.

Shown at right are three different implantable stimulator architectures.  At bottom left is a very small model, implantable within a 30 gram mouse.  At bottom left is a simple architecture with low power outputs, specifically designed to stimulate normally innervated muscle, to control activity for metabolic experiments or to cause fiber type conversion.  At top is a much more sophisticated model with an embedded DC-DC converter, an infra-red optical transcutaneous data link, and a capacitive discharge high voltage output buffer.  The added power and sophistication of the upper model is required to adequately stimulate chronically-denervated skeletal muscle.  Not shown is the newest model, currently under development, which includes on board 12-bit analog-to-digital converters and a bi-directional infra-red transcutaneous data link.  All of my implantable devices are built using the Microchip PIC16CXX series 8-bit microcontrollers.  These devices can operate for up to 7 months on a single set of batteries.

These stimulators have application in a very wide range of experiments, including the maintenance of mass and force in denervated skeletal muscles, functional electrical stimulation, fiber type conversion and in vivo tissue re-engineering, data collection and transmission on un-tethered animals, contraction-induced injury in dystrophic mice, glucose metabolism resulting controlled contractile activity, control of activity-dependant gene expression in muscle, and tissue pre-engineereing for the use of intact native whole muscles as tissue actuators in robotic and prosthetic devices.