VLSI and Circuits, Embedded and Hardware Systems Commons^™

Pseudo-Soft-Switching Switched-Capacitor Drive Circuits For Small-Scale Dielectric Actuators, Yanqiao Li

Dartmouth College Ph.D Dissertations

Applications including micro-robotics and haptics have motivated extensive exploration of dielectric actuators due to their high bandwidth and high efficiency at cm and mm scales. To maximize their benefits, dielectric actuators, including piezoelectric and electrostatic actuators, typically require high driving voltages, ranging from 100V to several kV. Generating such high driving voltages presents a challenge for drive circuits, particularly when powered by a small battery. Dielectric actuators are predominantly capacitive in most circumstances, necessitating the drive circuits to deliver and recover reactive energy for efficient operation. In some applications, such as micro-robotics, the drive circuits may need to have a …

Hybrid Dc-Dc Converters For Soft Charging Capacitive Actuators: Modeling, Analysis And Design, Bahlakoana Mabetha

Dartmouth College Ph.D Dissertations

Recent trends in haptics, microrobotics and ultrasound technology have shown an increasing use of piezoelectric and other electrostatic actuators. These actuators are suited for miniaturized applications due to their high power density and favorable scalability at a small size. Their electrical impedance at lower frequency (their typical operating range) is capacitive, therefore, they can be modeled as capacitive loads.

The driving circuits for capacitive actuators need to deliver and recover (bidirectional) dominantly reactive power, unlike typical power electronics converters for resistive loads which deliver (unidirectional) real power to the load. Therefore, the circuits, operation, and optimization required to drive these …

Towards A Wearable Device For Measuring Impedance Plethysmography Of The Radial Artery, Pritom Chowdhury

Dartmouth College Master’s Theses

Recent advancements in bioimpedance technology have demonstrated significant promise in the application of cardiac health monitoring. This research explores the design and development of a forearm-based wearable bioimpedance device for non-invasive measurement of heart rate and respiratory rate at an accuracy level comparable to medical-grade monitors. It utilizes a tetrapolar electrode configuration to analyze bioimpedance changes in the radial artery due to blood flow.

An ongoing aspect of this work involves the preliminary development of an embedded framework intended to integrate signal generation, acquisition, and processing within the device to achieve compact and efficient system design, anticipated to contribute to …

Modeling And Control Of Direct-Conversion Hybrid Switched-Capacitor Dc-Dc Converters, Ziyu Xia

Dartmouth College Ph.D Dissertations

Efficient power delivery is increasingly important in modern computing, communications, consumer and other electronic systems, due to the high power demand and thermal concerns accompanied by performance advancements and tight packaging. In pursuit of high efficiency, small physical volume, and flexible regulation, hybrid switched-capacitor topologies have emerged as promising candidates for such applications. By incorporating both capacitors and inductors as energy storage elements, hybrid topologies achieve high power density while still maintaining soft charging and efficient regulation characteristics. However, challenges exist in the hybrid approach. In terms of reliability, each flying capacitor should be maintained at a nominal `balanced' voltage …

The Design Of Cmos Front-End Amplifiers For Electrical Impedance Applications, Yueh-Ching Teng

Dartmouth College Ph.D Dissertations

Electrical Impedance Tomography (EIT) is a medical imaging methodology that does not need any kind of ionizing radiation. It is significantly cheaper and smaller than Computerized Tomography (CT) or Magnetic Resonance Imaging (MRI). These advantages make EIT particularly suitable for emerging applications like the continuous medical imaging and telemonitoring of organ function. Current bench-top EIT systems are bulky and require shielded cables to interface with measurement electrodes. The cable introduces parasitic capacitances which shunt the desired signals and degrade the accuracy of the measurements. A EIT system based on application-specific integrated circuits (ASICs) can reduce the parasitic and stray capacitance …