Electrostatic energy harvesting by droplet-based multi-phase microfluidics

Abstract

This paper presents an energy scavenging technique, merging microfluidics with electrostatic energy harvesting. The method employs droplet-based microflow of two phases with different electrical permittivities, resulting in a capacitance change across the microchannel, to harvest electrical energy. The technique is implemented on 3 mm wide, 1 mm deep minichannels. It is shown that 0.4 nW can be harvested using a single electrode pair, with air and water as the two phases flowing at 1 ml/min. The generated power can be increased significantly by microscale implementation, where the number of electrodes can also be increased for further improvement.

Fluidic Active Transducer for Electricity Generation

“…This novel fluidic active transducer has several strength points. First, it has very simple structure and fabrication method compared with previous works 6 7 8 9 10 . Second, until now, most of the electricity generators have been water vibrational generators 22 23 24 but FEG can be operated under various channel flow conditions conforming to flows found in daily life and in nature.…”

“…Specially, interest in electricity generation with flows in a channel has been recently increased in the fields of micro energy harvesting and sensing 6 7 8 9 10 . Several techniques such as variation of capacitance 6 7 , reverse electro-wetting 8 and electro kinetic flow 9 10 have been studied.…”

“…Specially, interest in electricity generation with flows in a channel has been recently increased in the fields of micro energy harvesting and sensing 6 7 8 9 10 . Several techniques such as variation of capacitance 6 7 , reverse electro-wetting 8 and electro kinetic flow 9 10 have been studied. However, there are several drawbacks to the variation of capacitance and reverse electro-wetting techniques, which are the necessity of external sources such as a bias voltage or pre-charging processes to maintain a voltage difference in capacitor 6 7 8 .…”

“…Several techniques such as variation of capacitance 6 7 , reverse electro-wetting 8 and electro kinetic flow 9 10 have been studied. However, there are several drawbacks to the variation of capacitance and reverse electro-wetting techniques, which are the necessity of external sources such as a bias voltage or pre-charging processes to maintain a voltage difference in capacitor 6 7 8 . The energy generation of electro kinetic flows uses a pressure gradient in nano-sized channel arrays as a streaming potential 9 10 , which needs complicated fabrication processes such as a micro- or nano-patterning process for nano-channel arrays.…”

Electrostatic Energy Harvester Using Magnetically Actuated Liquid Dielectric Layers

“…Bu et al [6] and Choi et al [7] reported on a liquidbased energy harvester, suitable for low vibration frequencies of less than 10 Hz. Others have demonstrated electrostatic energy harvesting that uses the change in capacitance across a microchannel due to the flow of liquids [8], [9]. However, there were limitations in obtaining high output power with those harvesters because of the small and slow change in capacitance.…”