A pressure driven electric energy generator exploiting a micro- to nano-scale glass porous filter with ion flow originating from water.

We demonstrated a pressure driven energy harvesting device using water and that features a glass filter with porous channels. We employed powder sintering to fabricate the glass filter (2 cm diameter, 3 mm thickness) by packing a powder of borosilicate glass particles into a carbon mold and then thermally fusing this at 700°C under pressure. In constant flow rate experiment, the optimum average pore radius of the filter for power generation was 12 μm. Using this filter, power of 3.8 mW (27 V, 0.14 mA, 0.021% energy efficiency) was generated at a water flow speed of 50 mm/s. In constant pressure experiment, a power generator was equipped with a foot press unit with a 60 kg weight (830 kPa) and 50 mL of water. The optimum average pore radius for power generation in this experiment was 12 μm and power of 4.8 mW (18 V, 0.26 mA, 0.017% energy efficiency) was generated with 1.7 s duration. This was enough power for direct LED lighting and the capacitors could store enough energy to rotate a fan and operate a wireless communicator. Our pressure driven device is suitable for energy harvesting from slow movements like certain human physiological functions, e.g. walking.