A novel transparent UWB antenna for photovoltaic solar-panel integration and RF energy harvesting is proposed in this paper. Since the approval by the Federal Communications Committee (FCC) in 2002, much research has been undertaken on ultrawide band (UWB) technology especially for wireless communications. However, in the last decade, UWB has also been proposed as a power harvester. In this paper, a transparent cone top tapered slot antenna covering the frequency range from 2.2 GHz to 12.1 GHz is designed and fabricated to provide UWB communications whilst integrated onto to solar panels as well as harvest electromagnetic waves from free space and convert them into electrical energy. The antenna when sandwiched between an a-Si solar panel and glass is able to demonstrate a quasi Omnidirectional pattern that is characteristic of a UWB. The antenna when connected to a 2.55-GHz rectifier is able to produce 18 mV DC in free space and 4.4 mV DC on glass for an input power of 10 dBm at a distance of 5 cm. Although the antenna presented in this paper is a UWB antenna, only an operating range of 2.49 to 2.58 GHz for power scavenging is possible due to the limitation of the narrowband rectifier used for the study.

Cochlear hair cells are critical for the conversion of acoustic into electrical signals and their dysfunction is a primary cause of acquired hearing impairments, which worsen with aging. Piezoelectric materials can reproduce the acoustic-electrical transduction properties of the cochlea and represent promising candidates for future cochlear prostheses. The majority of piezoelectric hearing devices so far developed are based on thin films, which have not managed to simultaneously provide the desired flexibility, high sensitivity, wide frequency selectivity, and biocompatibility. To overcome these issues, we hypothesized that fibrous membranes made up of polymeric piezoelectric biocompatible nanofibers could be employed to mimic the function of the basilar membrane, by selectively vibrating in response to different frequencies of sound and transmitting the resulting electrical impulses to the vestibulocochlear nerve. In this study, poly(vinylidene fluoride-trifluoroethylene) piezoelectric nanofiber-based acoustic circular sensors were designed and fabricated using the electrospinning technique. The performance of the sensors was investigated with particular focus on the identification of the resonance frequencies and acoustic-electrical conversion in fibrous membrane with different size and fiber orientation. The voltage output (1–17 mV) varied in the range of low resonance frequency (100–400 Hz) depending on the diameter of the macroscale sensors and alignment of the fibers. The devices developed can be regarded as a proof-of-concept demonstrating the possibility of using piezoelectric fibers to convert acoustic waves into electrical signals, through possible synergistic effects of piezoelectricity and triboelectricity. The study has paved the way for the development of self-powered nanofibrous implantable auditory sensors.

We report the development of a novel multi-tier interface which enables the wireless, noninvasive transfer of sufficient amounts of power as well as the collection and transmission of data from low-power, deeply implantable analog sensors. The interface consists of an inductive coupling subsystem and an ultrasonic subsystem. The designed and experimentally verified inductive subsystem ensures that 5 W of power is transferred across 10 mm of air gap between a single pair of PCB spiral coils with an efficiency of 83% using our prototype CMOS logic gate-based driver circuit. The implemented ultrasonic subsystem, based on ultrasonic PZT ceramic discs driven in their low-frequency, radial/planar-excitation mode, further ensures that 29 μW of power is delivered 70 mm deeper inside a homogenous liquid environment-with no acoustic matching layer employed-with an efficiency of 1%. Overall system power consumption is 2.3 W. The implant is intermittently powered every 800 msec; charging a capacitor which provides sufficient power for a duration of ~ 18 msec; sufficient for an implant μC operating at a frequency of 500 KHz to transmit a nibble (4 bits) of digitized sensed data.

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Silicon-germanium (SiGe) heterojunction metal-oxide-semiconductor field-effect transistors (SiGe HMOSFETs) have been successfully fabricated on Si substrate. The semiconductor heterostructure, which was grown by gas-source molecular beam epitaxy (GS-MBE), was initiated by the deposition of a Si 0.7 Ge 0.3 ''virtual substrate''. The n-type transistors were fabricated using a standard MOS process. The channel is a thin, undoped layer of strained Si and is buried below an arsenic-doped Si 0.7 Ge 0.3 layer, which provides the carriers. The devices exhibited excellent current-voltage (I-V) characteristics in terms of transconductance and drain current, with no breakdown or leakage. A level-1 model was extracted, for use in circuit design. The results suggest that the realisation of buried-channel SiGe n-HMOSFETs is feasible in MOS processes. These devices are of particular importance in analogue applications. #