Inductively Coupled CMOS Power Receiver For Embedded Microsensors

Inductively coupled power transfer can extend the lifetime of embedded microsensors that save costs, energy, and lives. To expand the microsensors' functionality, the transferred power needs to be maximized. Plus, the power receiver needs to handle wide coupling variations in real applications. Therefore, the objective of this research is to design a power receiver that outputs the highest power for the widest coupling range. This research proposes a switched resonant half-bridge power stage that adjusts both energy transfer frequency and duration so the output power is maximally high. A maximum power point (MPP) theory is also developed to predict the optimal settings of the power stage with 98.6% accuracy. Finally, this research addresses the system integration challenges such as synchronization and over-voltage protection. The fabricated self-synchronized prototype outputs up to 89% of the available power across 0.067%~7.9% coupling range. The output power (in percentage of available power) and coupling range are 1.3× and 13× higher than the comparable state of the arts.Ph.D

Effect of the micromoulding process conditions on polymer flow behavior within a variable thickness microcavity

Fast time to market along with high level of automation and versatility made microinjection moulding, by far, a favorite technique for the mass production of microplastic components. In the microimpressions, very high shear rates develop, eventually leading to excessive shear heating and consequently to less predictable flow behaviour comparing to conventional injection moulding. In this study, the flow behaviour within a variable thickness microimpression is investigated by monitoring pertinent process parameters such as cavity temperature and pressure. A micromoulding insert with a variable thickness was designed, fabricated and instrumented with pressure and temperature sensors. Full factorial design of experiment (DOE) was carried out to optimize the filling of the microimpression. The study with acrylonitrile butadiene styrene (ABS) suggests that the mould temperature plays an important role in the microimpression filling regardless of its thickness. In addition, the microinjection moulding process was monitored in terms of the cavity pressure and temperature, enabling closer assessment of the polymer flow state in the microimpression.Fundação para a Ciência e Tecnologia, project PTDC/EME/TME/66227/2006 and PhD Individual Grant SFRH/BP/45585/2008

Micro guidance and control synthesis: New components, architectures, and capabilities

New GN&C (guidance, navigation and control) system capabilities are shown to arise from component innovations that involve the synergistic use of microminiature sensors and actuators, microelectronics, and fiber optics. Micro-GN&C system and component concepts are defined that include micro-actuated adaptive optics, micromachined inertial sensors, fiber-optic data nets and light-power transmission, and VLSI microcomputers. The thesis is advanced that these micro-miniaturization products are capable of having a revolutionary impact on space missions and systems, and that GN&C is the pathfinder micro-technology application that can bring that about

Real-time monitoring of metabolic function in liver-on-chip microdevices tracks the dynamics of mitochondrial dysfunction

Microfluidic organ-on-a-chip technology aims to replace animal toxicity testing, but thus far has demonstrated few advantages over traditional methods. Mitochondrial dysfunction plays a critical role in the development of chemical and pharmaceutical toxicity, as well as pluripotency and disease processes. However, current methods to evaluate mitochondrial activity still rely on end-point assays, resulting in limited kinetic and prognostic information. Here, we present a liver-on-chip device capable of maintaining human tissue for over a month in vitro under physiological conditions. Mitochondrial respiration was monitored in real time using two-frequency phase modulation of tissue-embedded phosphorescent microprobes. A computer-controlled microfluidic switchboard allowed contiguous electrochemical measurements of glucose and lactate, providing real-time analysis of minute shifts from oxidative phosphorylation to anaerobic glycolysis, an early indication of mitochondrial stress. We quantify the dynamics of cellular adaptation to mitochondrial damage and the resulting redistribution of ATP production during rotenone-induced mitochondrial dysfunction and troglitazone (Rezulin)-induced mitochondrial stress. We show troglitazone shifts metabolic fluxes at concentrations previously regarded as safe, suggesting a mechanism for its observed idiosyncratic effect. Our microfluidic platform reveals the dynamics and strategies of cellular adaptation to mitochondrial damage, a unique advantage of organ-on-chip technology

Electrical Power Generation Using Footsteps

Electricity is the most general forms of energy used across the world. This paper focuses on designing a setup that leads to the generation of electrical energy which is going to waste when humans are walking. Footsteps are an untapped natural resources. This generated energy is, however, costeffective and nonhazardous for human. Electrical energy can be produced by converting mechanical energy using footsteps. Generating the electric power through the fabrication of footstep arrangement by a prototype comprises of a pipe, nozzle, unidirectional valve, water reservoir, turbine, and DC motor. Whenever pressure is exerted on the reservoir, water flows through the nozzle into the turbine and generates electrical energy. This energy is stored in the battery. This project will reduce the global warming and load shedding in a much cleaner cost-effective way. Since this project is related directly to the human movement, the weight of the setup is a crucial factor

Self-sensing composites: in-situ detection of fibre fracture

The primary load-bearing component in a composite material is the reinforcing fibres. This paper reports on a technique to study the fracture of individual reinforcing fibres or filaments in real-time. Custom-made small-diameter optical fibres with a diameter of 12 (±2) micrometres were used to detect the fracture of individual filaments during tensile loading of unreinforced bundles and composites. The unimpregnated bundles were end-tabbed and tensile tested to failure. A simple technique based on resin-infusion was developed to manufacture composites with a negligible void content. In both cases, optical fibre connectors were attached to the ends of the small-diameter optical fibre bundles to enable light to be coupled into the bundle via one end whilst the opposite end was photographed using a high-speed camera. The feasibility of detecting the fracture of each of the filaments in the bundle and composite was demonstrated. The in-situ damage detection technique was also applied to E-glass bundles and composites; this will be reported in a subsequent publication

Wireless event-recording device with identification codes

A wireless recording device can be interrogated to determine its identity and its state. The state indicates whether a particular physical or chemical event has taken place. In effect, the physical or chemical event is recorded by the device. The identity of the device allows it to be distinguished from a number of similar devices. Thus the sensor device may be used in an array of devices that can be probed by a wireless interrogation unit. The device tells the interrogator who it is and what state it is in. The interrogator can thus easily identify particular items in an array that have reached a particular condition