Generator developed for harvesting energy from droplets  July 8, 2020 An international team of researchers (the Netherlands, China) has designed a charge trapping‐based electricity generator (CTEG) for passive energy harvesting from water droplets with high efficiency. The hydrophobic fluoropolymer films utilized in CTEG are pre‐charged by a homogeneous electrowetting‐assisted charge injection method, allowing an ultrahigh negative charge density. By connecting the bottom electrode and top electrode of a Pt wire, instantaneous current is generated from continuously falling water droplets. CTEG devices have shown robustness without appreciable degradation for intermittent testing during 100 days. The approach is applicable for energy harvesting from wave‐like oscillatory fluid motion. it […]

Wide-band-gap semiconductors could harvest sunlight underwater

Physics World  April 17, 2020 Using detailed-balance calculations researchers at the University of New York have shown that underwater solar cells can exhibit efficiencies from ∼55% in shallow waters to more than 65% in deep waters, while maintaining a power density >5 mW cm −2. They showed that the optimum band gap of the solar cell shifts by ∼0.6 eV between shallow and deep waters and plateaus at ∼2.1 eV at intermediate depths, independent of geographical location. This wide range in optimum band-gap energies opens the potential for a library of wide-band-gap semiconductors to be used for high-efficiency underwater solar […]

Drones Use Radio Waves to Recharge Sensors While in Flight

IEEE Spectrum  April 17, 2020 An international team of researchers (Lebanon, Italy) has developed and implemented a RF energy harvesting and wake-up system that scavenges a 2.4 GHz signal from a UAV. It can deliver power wirelessly to remote sensors. The signal transmitted by the UAV is harvested and rectified to DC voltage to power a sensor on the ground. Additionally, the UAV modulates the transmitted signal to encode an address that triggers a particular sensor from sleep mode to active mode. Charging can be initiated from input power levels as low as -18.2~dBm and a sensor can be triggered […]

Penn Engineering’s New Scavenger Technology Allows Robots to ‘Eat’ Metal for Energy

University of Pennsylvania,  April 6, 2020 The metal-air scavenger developed by researchers at the University of Pennsylvania works like a battery by providing power by repeatedly breaking and forming a series of chemical bonds and a harvester as the power is supplied by energy in the chemical bonds in metal and air surrounding the metal-air scavenger. They showed that a range of hydrogel electrolyte compositions can be combined with air cathodes to extract 159, 87, and 179 mAh/cm2 capacities from aluminum, zinc, and steel surfaces at up to 130, 81, and 25 mW/cm2 power densities, which exceed the power density […]

Untwisting plastics for charging internet-of-things devices

Science Daily  April 16, 2020 To use body heat to charge some types of micro-devices and sensors lightweight, non-toxic, wearable, and flexible thermoelectric generators are required. Japan studied the thermoelectric properties of highly conductive thiophene-based polymer, called PBTTT. They doped the polymer with a thin ion electrolyte gel, which is known to improve conductivity that infiltrates the polymer successfully when a specific electric voltage is applied. They found that, without the electrolyte gel, the PBTTT chain is highly twisted. Doping it with a critical amount of electrolyte untwists the chain and creates links between its crystalline parts, improving electron conductivity. […]

Energy-harvesting design aims to turn Wi-Fi signals into usable power  March 30,2020 Existing rectifiers are mostly based on semiconductor diodes, with limited applicability to small-voltage or high-frequency inputs. Researchers at MIT present an alternative approach to current rectification that uses the intrinsic electronic properties of quantum crystals without using semiconductor junctions. They identified a previously unknown mechanism for rectification from skew scattering due to the inherent chirality of itinerant electrons in time-reversal invariant but inversion-breaking materials. Their calculations reveal large, tunable rectification effects in graphene multilayers and transition metal dichalcogenides. Their work demonstrates the possibility of realizing high-frequency rectifiers by rational material design and quantum wave function engineering…read more. […]

New green technology generates electricity ‘out of thin air’  February 17, 2020 Researchers at UMass Amherst have developed a thin-film device they call “Air-gen”, made from nanometre-scale protein wires harvested from the microbe Geobacter sulfurreducens that can generate continuous electric power in the ambient environment. The devices produce a sustained voltage of around 0.5 volts across a 7-micrometre-thick film, with a current density of around 17 microamperes per square centimetre. According to the researchers the driving force behind this energy generation is a self-maintained moisture gradient that forms within the film when the film is exposed to the humidity that is naturally present in air. Connecting several devices […]

Movement of a liquid droplet generates over 5 volts of electricity

EurekAlert  February 13, 2020 Researchers in Japan have demonstrated that using molybdenum disulfide instead of graphene as the active material in the generator makes it possible to generate over 5 volts of electricity from a liquid droplet. They made a large area single -layer MoS2 film with polystyrene film as bearing material, by chemical vapor deposition using a sapphire substrate with molybdenum oxide (MoO3) and sulphur powders. The film made it easy to transfer the synthesized MoS2 film to the surface. The generator is flexible enough to be installed on the curved inner surface of plumbing and is thus expected […]

With nanogenerators, static electricity as strong as lightening can be saved in a battery

Nanowerk  February 6, 2020 Researchers in South Korea have developed a one-step process of thermal nanoimprinting and simultaneous electric poling to increase the total energy obtained by each cycle of triboelectric nanogenerators (TENGs) with a ferroelectric thermoplastic polymer. They invented an integrated circuit that converted temporary and unstable electric energy generated by a triboelectric nanogenerator into reliable power source. They demonstrated that even when 2.5 µW of energy was input, the conversion efficiency recorded over 70% and that stable power of 1.8V was obtained without external power supply when this circuit was used. This amount of power was enough to […]