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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012., Cataloged from PDF version of thesis., Includes bibliographical references (p. 167-174)., Trends in the medical industry have created a growing demand for implantable medical devices. In particular, the need to provide medical professionals a means to continuously monitor bio-markers over long time scales with increased precision is paramount to efficient healthcare. To make medical implants more attractive, there is a need to reduce their size and power consumption. Small medical implants would allow for less invasive procedures and greater comfort for patients. The two primary limitations to the size of small medical implants are the batteries that provide energy to circuit and sensor components, and the antennas that enable wireless communication to terminals outside of the body. In this work we present energy management and low-power techniques to help solve the engineering challenges posed by using ultracapacitors for energy storage. A major problem with using any capacitor as an energy source is the fact that its voltage drops rapidly with decreasing charge. This leaves the circuit to cope with a large supply variation and can lead to energy being left on the capacitor when its voltage gets too low to supply a sufficient supply voltage for operation. Rather than use a single ultracapacitor, we demonstrate higher energy utilization by splitting a single capacitor into an array of capacitors that are progressively reconfigured as energy is drawn out. An energy management IC fabricated in 180-nm CMOS implements a stacking procedure that allows for more than 98% of the initial energy stored in the ultracapacitors to be removed before the output voltage drops unsuitably low for circuit operation. The second part of this work develops techniques for wide-input-range energy management. The first chip implementing stacking suffered an efficiency penalty by using a switchedcapacitor voltage regulator with only a single conversion ratio. In a second implementation, we introduce a better solution that preserves efficiency performance by using a multiple conve, by William R. Sanchez., Ph.D.

We present the first known energy management IC to allow low-power systems, such as biomedical implants, to optimally use ultracapacitors instead of batteries as their chief energy storage elements. The IC, fabricated in a 0.18 μm CMOS process, consists of a switched-capacitor DC-DC converter, a 4 nW bandgap voltage reference, a high-efficiency rectifier to allow wireless recharging of the capacitor bank, and a switch matrix and digital control circuitry to govern the stacking and unstacking of the ultracapacitors. The stacking procedure allows for more than 98% of the initial energy stored in the capacitors to be removed before the output voltage drops unsuitably low. The DC-DC converter achieves a peak efficiency of 51% for loads between 10 and 100 μW, operates for input voltages between 1.25 and 2.5 V.

Ultralow-power electronics for cardiac monitoring make possible the development of new light-weight and low-cost devices that are ideal for long-term medical measurements and home-based tele-monitoring services. Nowadays, these devices are seen as a critical technology for reducing health-care costs. In this paper, we present several methods for reducing power consumption while retaining the precision necessary for cardiac monitoring. In particular, we describe a micropower electrocardiograph, an ultralow-power pulse oximeter, an ultralow-power phonocardiograph, an integrated-circuit switched-capacitor model of the heart, and an ultracompact and efficient lithium-ion battery charger. These components are, to our knowledge, currently the most power-efficient or minimal-size designs present in the literature in each respective category.

New electronics for non-invasive medical monitoring promise low-cost, maintenance-free, and lightweight devices. These devices are critical in long-term medical measurements and in home-based tele-monitoring services, which are extremely important for the reduction of health care costs. Here, we present several methods for reducing power consumption while retaining precision. In particular, we focus on the monitoring of the heart-because of its importance-and we describe a micropower electrocardiograph, an ultra-low-power pulse oximeter, an ultra-low-power phonocardiograph, an integrated-circuit switched-capacitor model of the heart, and a low-power RF-antenna-powered CMOS rectifier for energy harvesting. We also introduce an ultra-low-power platform for medical monitoring that enables the integration of monitoring circuitry in a wireless, low-cost, and battery-free device, and describe a method for audio localization of the device in case of a medical alarm.

The National Museum of the Pacific War presents an oral interview with William R. Sanchez. Born in Texas in 1918, Sanchez joined the Civilian Conservation Corps (CCC) in 1938. He was drafted into the Army in 1940 and elected to serve in the Philippines. He was assigned to the 59th Regiment, Coast Artillery, Battery D and later Battery H at Fort Mills (Corregidor). He was then assigned to Army Intelligence in the Harbor Defense Headquarters. He recounts how the Army Intelligence at Corregidor provided advance notification of the Japanese force on its way to attack Pearl Harbor. He describes participating in the battle for Corregidor, being taken prisoner in the Malinta Tunnel, and his role in disposing of an American flag after the surrender to the Japanese. He discusses the treatment and living conditions he experienced as a prisoner of war. He was held captive at Bilibid Prison and Cabanatuan in the Philippines. He was transported aboard the Totorri Maru, a hell ship, to Formosa. He was then relocated to Camp Omori near Tokyo, Japan where he befriended Gregory �Pappy� Boyington and Louis Zamperini; was beaten by �the Wiley Bird� (Mutsuhiro Watanabe); and encountered Premier Tojo. He discusses his release when the war ended, return to the United States, and discharge. He shares anecdotes about participating in a regimental boxing match and meeting the father of the Japanese officer who captured him at Corregidor.

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, June 2007., This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections., "May 2007.", Includes bibliographical references (p. 79-82)., We have implemented a segment of an RF transmitter signal chain in discrete components using bipolar transistors. We formulated both a broadband amplifier and mixer as mathematical programs (MP) and extracted Pareto-optimal (PO) [1-3] tradeoff surfaces. Abstracting these PO surfaces in place of the blocks at the system level, we have demonstrated a new hierarchical system design methodology. Furthermore, the optimization, simulation, and measured results are consistent at all levels of hierarchy. Keywords: System design, optimization, geometric programming, analog circuits, Pareto-optimal., by William R. Sanchez., M.Eng.