WIDEBAND ENERGY HARVESTING FOR IMPLANTABLE BIOMEDICAL APPLICATIONS

In this paper, a nonresonant electromagnetic micro-generator is proposed. The proposed device is capable of converting nonresonant environmental vibrations to electrical power. The energy harvester could generate output power from heartbeat, human leg and arm motion. The proposed energy harvester uses Frequency up CONVersion technique (FCONV) to improve the bandwidth of the device. The results approve the high bandwidth of the proposed method. The micro-generator is designed by micro-electro-mechanical systems (MEMS) methods. Consequently, the volume of the power harvester is minimized and power density is maximized. The new configuration of energy harvester with imposed motion trigger is proposed. Output power, bandwidth and performance of the designed micro-power harvester are discussed. The proposed micro-generator exhibits higher bandwidth in comparison with resonant, multi-resonant and tunable bandwidth structures. The nonresonant device is designed using FCONV to convert 1–3[Formula: see text]Hz heartbeat mechanical vibrations to output electrical power. The optimum upconverted mechanical vibration frequency is 60[Formula: see text]Hz and the output voltage frequency is 120[Formula: see text]Hz. The peak output electrical power of FCONV is 17.75[Formula: see text][Formula: see text]W. For 1[Formula: see text]Hz, 2[Formula: see text]Hz and 3[Formula: see text]Hz mechanical vibration with imposed motion trigger, average output powers are 1.60[Formula: see text][Formula: see text]W, 3.81[Formula: see text][Formula: see text]W and 5.19[Formula: see text][Formula: see text]W, respectively. The achieved results illustrate that the proposed FCONV method exhibits better and wider frequency response in comparison with different methods. The designed device can be utilized to supply implantable biomedical sensors. Also, the heat generation of the device is studied. The results illustrate that the temperature rise of the micro-generator remains in the normal human body temperature range. Hence, the proposed power harvester is biocompatible.

Shoe embedded air pump type piezoelectric power harvester

Shoe embedded air pump type piezoelectric power harvester

Shoe embedded air pump type piezoelectric power harvester

Shoe embedded air pump type piezoelectric power harvester

Improving Power Density Of A Class Of Piezoelectic Power Harvesters Through Proof Mass Optimization

This thesis presents a method to optimize the proof mass of the cantilever piezoelectric power harvester. With this novel proof mass, a lower fundamental frequency and a higher power density (output power per unit volume) were achieved. Prototypes of 0.242 cm³ in volume were fabricated and tested and a power density of 1446 μW/cm³ was achieved for sinusoidal excitation of 0.75 g. It was experimentally shown that the new power harvester lowered the fundamental frequency by 26% and increased the power density by 68% in comparison with the conventional harvesters. When tested on a shoe, the new power harvester generated an average power of 48.4 μW at 3.0 mph walking speed on a treadmill.

Improving Power Density Of A Class Of Piezoelectic Power Harvesters Through Proof Mass Optimization

This thesis presents a method to optimize the proof mass of the cantilever piezoelectric power harvester. With this novel proof mass, a lower fundamental frequency and a higher power density (output power per unit volume) were achieved. Prototypes of 0.242 cm³ in volume were fabricated and tested and a power density of 1446 μW/cm³ was achieved for sinusoidal excitation of 0.75 g. It was experimentally shown that the new power harvester lowered the fundamental frequency by 26% and increased the power density by 68% in comparison with the conventional harvesters. When tested on a shoe, the new power harvester generated an average power of 48.4 μW at 3.0 mph walking speed on a treadmill.

Automatic light-adjusting electrochromic device powered by perovskite solar cell

Electrochromic devices can modulate their light absorption under a small driving voltage, but the requirement for external electrical supplies causes response-lag. To address this problem, self-powered electrochromic devices have been studied recently. However, insensitivity to the surrounding light and unsatisfactory stability of electrochromic devices have hindered their critical applications. Herein, novel perovskite solar cell-powered all-in-one gel electrochromic devices have been assembled and studied in order to achieve automatic light adjustment. Two alkynyl-containing viologen derivatives are synthesized as electrochromic materials, the devices with very high stability (up to 70000 cycles) serves as the energy storage and smart window, while the perovskite solar cell with power-conversion-efficiency up to 18.3% serves as the light detector and power harvester. The combined devices can automatically switch between bleached and colored state to adjust light absorption with variable surrounding light intensity in real-time swiftly, which establish significant potentials for applications as modern all-day intelligent windows.