Master of Science in Electrical Engineering (MSEE)
Electrical and Computer Engineering
Bio-implantable devices such as heart pacers, gastric pacers and drug-delivery systems require power for carrying out their intended functions. These devices are usually powered through a battery implanted with the system or are wired to an external power source. In this work, a remote power delivery system (RPDS) is considered as a means to charge rechargeable batteries that power a Bio-implanted Electrical Stimulation System (BESS). A loosely coupled inductive power transmitter and receiver system has been designed to recharge batteries for a bio-implanted gastric pacer. The transmitter coil is periodically worn around the waist. The receiver coil, rechargeable batteries, battery-charging chip and the chip containing electrical stimulation circuitry form a bio-implanted hybrid integrated microsystem. The link efficiency between a transmitter coil and the implanted receiver coil when the diameters are markedly different is analyzed. A design methodology for RPDS is proposed based on the load and voltage required at the load. An analytical model is developed with the help of simple Matlab coding. A full wave rectifier with a voltage doubler circuit is used for the conversion of ac voltage to the required dc voltage. This dc voltage supplies power to a battery charging chip which is used to safely and appropriately charge a rechargeable Li-ion battery. For an input supply voltage of 17.67 V rms, operating frequency of 20 kHz and radial coplanar displacement between the coil axes of 7.5 inches, the maximum dc voltage and power obtained across a 65Ω load resistor are 9.65 V and 1.33 W respectively. For a radial coplanar displacement between the coil axes of 6 inches, a 3.7 V nominal, 150 mAh polymer lithium ion battery has been successfully charged in 1 hour and 40 minutes from an initial voltage of 3.39 V to 4.12 V with an input voltage of 19.81 V rms at 20 kHz. An attempt has been made to model coil parasitics at high frequency. Variations in the load power as a function of frequency and radial coplanar displacement of the axes are examined. Design strategies to optimize power delivery with given geometric constraints are considered.
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Gaddam, Venkat Reddy, "Remote power delivery for hybrid integrated Bio-implantable Electrical Stimulation System" (2005). LSU Master's Theses. 369.
Pratul K. Ajmera