Master of Sciences (Engineering), Case Western Reserve University, 2008, Electrical Engineering

A miniature, implantable, remote RF powering system for a small, un-tethered laboratory animal inside a cage is proposed. The proposed implantable device exhibits dimensions 6 mm x 6 mm x 2 mm and a mass of 100 mg including bio-compatible silicone coating. The external system consists of a Class-E power amplifier driving a tuned 15 cm x 25 cm coil. The implant device includes integrated “capacitor-free” RF to DC and power control circuitry. The full system provides 2 V VDD at up to 1 mA to implant electronics with < 200 μV DC variation, < 1 mV total RMS noise, and < 25 mVpp 4 MHz ripple and a 3 V supply to CMOS switches over a 10 cm x 20 cm operating region with an implant tilt angle of up to 60°. Additionally, an intelligent power control system is proposed that would reduce external system power consumption and cage temperature increase.

Committee: Darrin Young (Advisor); Frank Merat (Committee Member); Steven Garverick (Committee Member) Subjects: Electrical Engineering

Master of Sciences (Engineering), Case Western Reserve University, 2010, EECS - Electrical Engineering

An implantable wireless electromyogram sensing microsystem is developed for control of powered prostheses. RF powering and wireless data link enable real-time wireless operation. EMG signals are interfaced with a capacitively-coupled differential amplifier with 1 kHz bandwidth and an input-referred voltage noise power spectral density of 78 nV/√(Hz). The EMG signal is digitized by an on-chip 11 bit cyclic ADC. A Class-E amplifier operating at 8 MHz drives a 2-cm spiral coil, inductively coupled to an implantable 6-mm spiral coil. RF energy is rectified and regulated on-chip to produce stable 2.1V and 2.7V supplies. Manchester-encoded EMG data are transmitted by PSK modulation. The ASIC fabricated in the AMI 1.5μm CMOS process occupies 2.2x2.2 mm2 and dissipates 350 μW from RF powering. The system achieves 9.35 ENOB under battery powering and 8.6 ENOB under RF power, equivalent to an input detectable signal of 5.4 μVRMS and 9 μVRMS, respectively. In vivo testing shows a background EMG signal of 20 μVRMS, limiting system sensing resolution.

Committee: Darrin Young PhD (Advisor); Francis Merat PhD (Committee Member); Triolo Ronald PhD (Committee Member) Subjects: Biomedical Research; Electrical Engineering; Engineering; Rehabilitation

Doctor of Philosophy, Case Western Reserve University, 2009, EECS - Electrical Engineering

Genetic engineering of mice DNA sequences with real-time physiological monitoring has become the most critical research tool for identifying genetic variation susceptibility to diseases. Genetically engineered mice have been widely used as research vehicles with their physiological data being highly important for advanced biological research. Animal-based research results are expected to make a significant impact in treating similar human diseases. Due to the small size of a laboratory mouse, a miniature, light-weight, wireless, batteryless, and implantable multi-channel bio-sensing microsystem is developed to capture real-time accurate biological signals from an untethered animal in its natural habitat, thus eliminating stress and post-implant trauma-induced information distortion. A reliable radio frequency (RF) powering technique based on inductive coupling allows the batteryless microsystem to be achieved with a small form factor. The RF powering technique widely employed in biomedical applications typically relies on a set of external coil and an implantable coil with a relatively fixed position to inductively couple an external RF energy to an implanted microsystem. However, the proposed microsystem is implanted in a freely roaming mouse; hence resulting in a drastically changing magnetic coupling as the mouse moves and tilts its position with respect to the external stationary coil. Therefore, an optimized remote RF powering system with an adaptive control capability is designed and implemented. The prototype sensing microsystem can detect two vital signals, electrocardiogram (EKG) and core body temperature, and wirelessly transmit the information to a nearby receiver by employing a low power CMOS integrated circuits design with a minimal number of off-chip components for a high-level system integration. The overall implant unit exhibits a dimension of 9 mm x 7 mm x 3 mm and a weight of 400 mg including a pair of stainless steel EKG electrodes. A low power 2 (open full item for complete abstract)

Committee: Darrin Young (Advisor); Wen Ko (Committee Member); Francis Merat (Committee Member); Chung-Chiun Liu (Committee Member) Subjects: Electrical Engineering

Doctor of Philosophy, Case Western Reserve University, 2008, EECS - Electrical Engineering

Genetically engineered small laboratory animals with in vivo real-time physiological signals monitoring are ultimately crucial for system biology research to identify genetic variation susceptibility to various diseases and to develop effective treatment methods for similar human diseases. Blood pressure is one of the most important vital signals used in such research. However, there is no adequate solution for its chronic blood pressure monitoring to date. By merging MEMS technology and low power CMOS integrated circuits design through a high level system integration together with a conventional molding-based packaging technique, miniature, light-weight, wireless, batteryless, less-invasive, and implantable blood pressure sensing microsystems have been demonstrated for untethered small laboratory animals real-time monitoring. These critical features of the microsystem greatly suppress stress and post-implant trauma-induced information distortion. The proposed microsystem employs a miniature instrumented elastic sensing cuff, wrapped around a blood vessel, for blood pressure monitoring. The blood pressure is coupled into the sensing cuff caused by the vessel expansion and contraction. The microsystem can detect the pressure signal and wirelessly transmit the information to a nearby receiver with an adaptive RF powering capability to ensure a stable system power supply. The sensing technique avoids vessel penetration and substantially minimizes vessel restriction due to the soft cuff elasticity, thus attractive for long-term implant. A MEMS capacitive pressure sensor is designed and fabricated for its low temperature dependence, time stability, and zero DC power consumption. The integrated electronics consisting of a low power low-noise correlated-double-sampling capacitance-to-voltage converter, an 11-bit cyclic ADC, an adaptive RF powering system, an oscillator-based transmitter, and digital control circuitry have been designed and fabricated in a 1.5µm CMOS proces (open full item for complete abstract)

Committee: Darrin Young PhD (Advisor); Wen Ko PhD (Committee Member); Dominique Durand PhD (Committee Member); Steven Garverick PhD (Committee Member) Subjects: Electrical Engineering