The energy-harvesting ESG-LINK promises to power a sensing system indefinitely without batteries. (Photo: MicroStrain)

June 14, 2007 — MicroStrain, Inc. says its miniaturized energy-harvesting nodes operated successfully in the first-ever flight test of wireless strain sensors for damage tracking of rotating helicopter parts and other critical dynamic components.

MicroStrain’s ESG-LINK energy-harvesting sensing node features a precision time keeper, non-volatile memory for on-board data logging, and frequency agile IEEE 802.15.4 transceiver. Sampling rates, sample durations, sensor offsets, sensor gains and on-board shunt calibration are all wirelessly programmable. It promises to power a sensing system indefinitely, without the need for batteries, by converting the component’s cyclic strains into DC power using piezoelectric materials (patents issued and pending).

Recent flight tests on a Bell Helicopter Model 412 show that MicroStrain’s nodes will operate continually, without batteries, even under low energy generation conditions of straight and level helicopter flight. By continuously monitoring the strains on rotating components, the nodes can record operational loads, compute metal fatigue, and estimate remaining component life.

MicroStrain’s latest adaptive energy harvesting wireless sensors can sample pitch link static and dynamic loads at a rate of 32 samples/sec, then communicate these wireless data into the helicopter cabin, while consuming only 250 microwatts. Compared to conventional Wheatstone bridge signal conditioning electronics (which draw 72 milliwatts), MicroStrain’s node delivers an improvement of 288 fold.