Experimental Investigation of Continuous Usage Stability of Organic Polymer Electret in Micro Energy Harvesting

An electret is a stable dielectric material with a quasi-permanently embedded static electric charge or dipole polarisation. Theoretically, electrets should retain deposited charges for a long period of time. However, their charges are known to deteriorate with time due to polarising charge relaxation. There are organic and inorganic electrets. Cyclic Transparent Optical Polymer (CYTOP) is a good organic electret material with high charge density. Most studies on CYTOP charge stability has been concentrated mainly on storage, as it is believed that the same stability is exhibited in usage. We present the experimental investigation carried out, on storage stability, and continuous usage stability of CYTOP (grade A) electret. In this work, thin-film fabrication of four samples of CYTOP (CTL-809A) electret of same thickness was carried out; and corona charged with different voltages. One of them was stored and the others were used in vertical vibration based cantilever-electret micro-power generation for 52 days. Their surface charge decay (by surface potential measurement) with number of days was investigated. It was found out that the surface charges of the fabricated CYTOP electrets deteriorated faster with continuous usage than in storage.