它是美国国立医学图书馆（NLM）生产的国际性生物医学文献联机书目数据库，是美国国立医学图书馆MEDLARS系统30多个数据库中最大的一个数据库，是世界上最著名的生物医学数据库之一。其内容相当于3种印刷本检索刊物：《医学索引》（index medicus，IM）、《牙科文献索引》、《国际护理学索引》，收录了1966年以来的70多个国家4300多种期刊的题录和文摘共1100万条记录，

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In this paper, various ambient energy-harvesting technologies (solar, thermal, wireless, and piezoelectric) are reviewed in detail and their applicability in the development of self-sustaining wireless platforms is discussed. Specifically, far-field low-power-density energy-harvesting technology is thoroughly investigated and a benchmarking prototype of an embedded microcontroller-enabled sensor platform has been successfully powered by an ambient ultrahigh-frequency (UHF) digital TV signal (512-566 MHz) where a broadcasting antenna is 6.3 km away from the proposed wireless energy-harvesting device. A high-efficiency dual-band ambient energy harvester at 915 MHz and 2.45 GHz and an energy harvester for on-body application at 460 MHz are also presented to verify the capabilities of ambient UHF/RF energy harvesting as an enabling technology for Internet of Things and smart skins applications.

http://users.ece.gatech.edu/etentze/Procs14_Sangkil.pdf

Ambient RF Energy-Harvesting Technologies for Self-Sustainable Standalone Wireless Sensor Platforms

In this paper, various ambient energy-harvesting technologies (solar, thermal, wireless, and piezoelectric) are reviewed in detail and their applicability in the development of self-sustaining wireless platforms is discussed. Specifically, far- field low-power-density energy-harvesting technology is thor- oughly investigated and a benchmarking prototype of an embedded microcontroller-enabled sensor platform has been successfully powered by an ambient ultrahigh-frequency (UHF) digital TV signal (512-566 MHz) where a broadcasting antenna is 6.3 km away from the proposed wireless energy-harvesting device. A high-efficiency dual-band ambient energy harvester at 915 MHz and 2.45 GHz and an energy harvester for on-body application at 460 MHz are also presented to verify the capa- bilities of ambient UHF/RF energy harvesting as an enabling technology for Internet of Things and smart skins applications.

Ambient RF Energy-Harvesting Technologies for Self-Sustainable Standalone Wireless Sensor Platforms This paper presents various ambient energy-harvesting technologies and investigates their applicability in the development of self-sustaining wireless platforms.

Transiently powered computing devices such as RFID tags, kinetic energy harvesters, and smart cards typically rely on programs that complete a task under tight time constraints before energy starvation leads to complete loss of volatile memory. Mementos is a software system that transforms general-purpose programs into interruptible computations that are protected from frequent power losses by automatic, energy-aware state checkpointing. Mementos comprises a collection of optimization passes for the LLVM compiler infrastructure and a linkable library that exercises hardware support for energy measurement while managing state checkpoints stored in nonvolatile memory. We evaluate Mementos against diverse test cases in a trace-driven simulator of transiently powered RFID-scale devices. Although Mementos's energy checks increase run time when energy is plentiful, they allow Mementos to safely suspend execution when energy dwindles, effectively spreading computation across zero or more power failures. This paper's contributions are: a study of the runtime environment for programs on RFID-scale devices; an energy-aware state checkpointing system for these devices that is implemented for the MSP430 family of microcontrollers; and a trace-driven simulator of transiently powered RFID-scale devices.

/pdf/mementos-system-support-for-long-running-computation-on-rfid-44fepid0kj.pdf

Mementos: system support for long-running computation on RFID-scale devices

This paper presents a noninvasive wireless sensor platform for continuous health monitoring. The sensor system integrates a loop antenna, wireless sensor interface chip, and glucose sensor on a polymer substrate. The IC consists of power management, readout circuitry, wireless communication interface, LED driver, and energy storage capacitors in a 0.36-mm2 CMOS chip with no external components. The sensitivity of our glucose sensor is 0.18 μA·mm-2·mM-1. The system is wirelessly powered and achieves a measured glucose range of 0.05-1 mM with a sensitivity of 400 Hz/mM while consuming 3 μW from a regulated 1.2-V supply.

A 3- $\mu\hbox{W}$ CMOS Glucose Sensor for Wireless Contact-Lens Tear Glucose Monitoring

Biosensors present exciting opportunities in novel medical and scientific applications. However, sensor tags presented to date cannot interface with practical sensors, lack addressability, and/or require a custom (high-cost) interrogator. Our tag provides these features via ultra-low-power circuitry including a low-noise biosignal amplifier, unique tag ID generator, calibration-free 3 MHz oscillator, and EPC C1 Gen2 protocol compatibility. In addition to design details and measurement data from the fabricated IC, we present in vivo muscle temperature measurement from an untethered in-flight hawkmoth.

A 9 $\mu$ A, Addressable Gen2 Sensor Tag for Biosignal Acquisition

SOCWISP: A 9 μA, Addressable Gen2 Sensor Tag for Biosignal Acquisition

Muscles not only generate force. They may act as springs, providing energy storage to drive locomotion. Although extensible myofilaments are implicated as sites of energy storage, we show that intramuscular temperature gradients may enable molecular motors (cross-bridges) to store elastic strain energy. By using time-resolved small-angle x-ray diffraction paired with in situ measurements of mechanical energy exchange in flight muscles of Manduca sexta, we produced high-speed movies of x-ray equatorial reflections, indicating cross-bridge association with myofilaments. A temperature gradient within the flight muscle leads to lower cross-bridge cycling in the cooler regions. Those cross-bridges could elastically return energy at the extrema of muscle lengthening and shortening, helping drive cyclic wing motions. These results suggest that cross-bridges can perform functions other than contraction, acting as molecular links for elastic energy storage.

/pdf/the-cross-bridge-spring-can-cool-muscles-store-elastic-3ntuboblx9.pdf

The cross-bridge spring: can cool muscles store elastic energy?

SUMMARY A temperature gradient throughout the dominant flight muscle (dorsolongitudinal muscle, DLM 1 ) of the hawkmoth Manduca sexta , together with temperature-dependent muscle contractile rates, demonstrates that significant spatial variation in power production is possible within a single muscle. Using in situ work-loop analyses under varying muscle temperatures and phases of activation, we show that regional differences in muscle temperature will induce a spatial gradient in the mechanical power output throughout the DLM 1 . Indeed, we note that this power gradient spans from positive to negative values across the predicted temperature range. Warm ventral subunits produce positive power at their in vivo operating temperatures, and therefore act as motors. Concurrently, as muscle temperature decreases dorsally, the subunits produce approximately zero mechanical power output, acting as an elastic energy storage source, and negative power output, behaving as a damper. Adjusting the phase of activation further influences the temperature sensitivity of power output, significantly affecting the mechanical power output gradient that is expressed. Additionally, the separate subregions of the DLM 1 did not appear to employ significant physiological compensation for the temperature-induced differences in power output. Thus, although the components of a muscle are commonly thought to operate uniformly, a significant within-muscle temperature gradient has the potential to induce a mechanical power gradient, whereby subunits within a muscle operate with separate and distinct functional roles.

/pdf/temperature-gradients-drive-mechanical-energy-gradients-in-1dx6rbww5t.pdf

Temperature gradients drive mechanical energy gradients in the flight muscle of Manduca sexta

There is a significant dorso-ventral temperature gradient in the dominant flight muscles [dorsolongitudinal muscles (DLM1)] of the hawkmoth Manduca sexta during tethered flight. The mean temperature difference was 5.6°C (range=3.8–6.9°C) between the warmer, ventral-most subunits and the cooler, dorsal-most subunits. As force generation in muscle depends on temperature, the mechanical energy output of more dorsal subunits will differ from that of deeper and warmer muscle subunits. To test this hypothesis, we isolated the dorsal subunits and the ventral subunits and recorded both single and 25 Hz (wingbeat frequency) isometric contractions at a range of temperatures. Our data show that the contractile dynamics of the various regions of the DLM1 are similarly affected by temperature, with higher temperatures leading to reduced contraction times. Furthermore, using standard electromyography, we showed that the different regions are activated nearly simultaneously (mean time difference=0.22 ms). These observations suggest that the existence of a temperature gradient will necessarily produce a mechanical energy gradient in the DLM1 in M. sexta.

Nicole T. George

Papers

A 9 $\mu$ A, Addressable Gen2 Sensor Tag for Biosignal Acquisition

SOCWISP: A 9 μA, Addressable Gen2 Sensor Tag for Biosignal Acquisition

The cross-bridge spring: can cool muscles store elastic energy?

Temperature gradients drive mechanical energy gradients in the flight muscle of Manduca sexta

Temperature gradients in the flight muscles of Manduca sexta imply a spatial gradient in muscle force and energy output.