A system is proposed to convert ambient mechanical vibration into electrical energy for use in powering autonomous low power electronic systems. The energy is transduced through the use of a variable capacitor. Using microelectromechanical systems (MEMS) technology, such a device has been designed for the system. A low-power controller IC has been fabricated in a 0.6-m CMOS process and has been tested and measured for losses. Based on the tests, the system is expected to produce 8 W of usable power. In addition to the fabricated programmable controller, an ultra low-power delay locked loop (DLL)-based system capable of autonomously achieving a steady-state lock to the vibration frequency is described.

Low power design trends raise the possibility of using ambient energy to power future digital systems. A chip has been designed and tested to demonstrate the feasibility of operating a digital system from power generated by vibrations in its environment. A moving coil electromagnetic transducer was used as a power generator. Calculations show that power on the order of 400 W can be generated. The test chip integrates an ultra-low power controller to regulate the generator voltage using delay feedback techniques, and a low power subband filter DSP load circuit. Tests verify 500 kHz self-powered operation of the subband filter, a level of performance suitable for sensor applications. The entire system, including the DSP load, consumes 18 W of power. The chip is implemented in a standard 0.8 m CMOS process. A single generator excitation produced 23 ms of valid DSP operation at a 500 kHz clock frequency, corresponding to 11 700 cycles.

A system is proposed to convert ambient mechanical vibration into electrical energy for use in powering autonomous low-power electronic systems. The energy is transduced through the use of a variable capacitor, which has been designed with MEMS (microelectromechanical systems) technology. A low-power controller IC has been fabricated in a 0.6pm CMOS process and has been tested and measured for losses. Based on the tests, the system is expected to produce SpW of usable power.

Wireless distributed microsensor systems will1 enable the reliable monitoring and control of a variety of applications that range from medical and home security to machine diagnosis, chemical/biological detectiion and other military applications. The sensors have to be designed in a highly integrated fashion, optimizing across all levels of system abstraction, with the goal of rninimizing energy dissipation. This paper addresses some of the key design considerations for future microsensor f* .>y stems including the network protocols required for collalborative sensing and information distribution, system partitioning considering computation and communication costs, low energy electronics, power system design and energy harvesting techniques. IEEE 1999 CUSTOM INTEGRATED CIRCUITS CONFERENCE 0-7803-5443-5/99/$10.0001999 IEEE

Purpose Waste management for end-of-life (EoL) smartphones is a growing problem due to their high turnover rate and concentration of toxic chemicals. The versatility of modern smartphones presents an interesting alternative waste management strategy: repurposing. This paper investigates the environmental impact of smartphone repurposing as compared to traditional refurbishing using Life Cycle Assessment (LCA). Methods A case study of repurposing was conducted by creating a smartphone "app" that replicates the functionality of an in-car parking meter. The environmental impacts of this prototype were quantified using waste management LCA methodology. Studied systems included three waste management options: traditional refurbishment, repurposing using battery power, and repurposing using a portable solar charger. The functional unit was defined as the EoL management of a used smartphone. Consequential system expansion was employed to account for secondary functions provided; avoided impacts from displaced primary products were included. Impacts were calculated in five impact categories. Break-even displacement rates were calculated and sensitivity to standby power consumption were assessed.Results and discussion LCA results showed that refurbishing creates the highest environmental impacts of the three reuse routes in every impact category except ODP. High break-even displacement rates suggest that this finding is robust within a reasonable range of primary cell phone displacement. The repurposed smartphone in-car parking meter had lower impacts than the primary production parking meter. Impacts for battery-powered devices were dominated by use-phase charging electricity, whereas solar-power impacts were concentrated in manufacturing. Repurposed phones using battery power had lower impacts than those using solar power, however, standby power sensitivity analysis revealed that solar power is preferred if the battery charger is left plugged-in more than 20 % of the use period. Conclusions Our analysis concludes that repurposing represents an environmentally preferable EoL option to refurbishing for used smartphones. The results suggest two generalizable findings. First, primary product displacement is a major factor affecting whether any EoL strategy is environmentally beneficial. The benefit depends not only on what is displaced, but also on how much displacement occurs; in general, repurposing allows freedom to target reuse opportunities with high "displacement potential." Second, the notion that solar power is preferable to batteries is not always correct; here, the rank-order is sensitive to assumptions about user behavior.Keywords Avoided burden . End of life . E-waste . Reuse . Smartphone . System expansion . Waste management LCA IntroductionMillions of smartphones reach the end of their lives each year, making their responsible management an urgent environmental goal. Cell phone e-waste will continue to be a growing