ENERGY HARVESTING THROUGH REVERSE ELECTROWETTING -VINUTHNA C.R DEBOLINA SAHA

Electrowetting Electrowetting is a microfluidic phenomenon that changes the surface tension of the liquid on the solid surface on application of voltage. Electrowetting on dielectric(EWOD) – Liquid spreading on the dielectric surface is facilitated by electrically induced increase in the dielectric surface wettability. Motion of a conductive liquid on a dielectric-coated conductive substrate. Wettability change arises from the extra electrostatic energy that is associated with electrically charged liquid-solid interface.

Surface Energy ρ(sl effective)= ρ(sl0) – 1/2CV^2 cosϴ=cosϴ0 + 1/2CV^2 Wiki definition: Surface energy may be defined as the excess energy at the surface of the material compared to the bulk. ρ(sl effective)= ρ(sl0) – 1/2CV^2 cosϴ=cosϴ0 + 1/2CV^2

Contact angle The contact angle is the angle measured through the liquid, where a liquid/vapour interface meets a solid surface.

REVERSE ELECTROWETTING Converting mechanical energy of liquid motion into electrical current, thus achieving reverse electrowetting (REWOD). Constant bias voltage between droplet and electrode External mechanical actuation - moves the droplet to force the decrease of its overlap with the di-electric film coated electrode Tom Krupenkin and Ashley Taylor Converts pressure energy into electrical energy Liquid metal alloy- Galinstan Instep Nano power- research Basic concept - Change in contact angle and surface energy

How this works ? Capacitance(C) = €0A/d Cmax----->Cmin because of change in effective contact area.

How to make it efficient? More energy is generated when the conductivity of the fluid is more Electrode material of low conductivity is preferable Using more droplets thereby increasing the effective contact area Making the channel length more Challenges…. Energy produced is very less Device manufacturing for practical purposes

“Footfalls for phone calls” When we walk our body produces 40 watts of mechanical power as heat when our feet strike the ground. A special electricity-generating cushion placed inside the soles of a regular pair of shoes can transform some of that footfall power into several watts of electricity. Over the course of a single day, the generated energy, which gets stored in a small battery in the sole, provides enough electricity for a pedestrian to extend her smartphone’s battery life