An Exploratory Study on the Feasibility of a Foot Gear Type Energy Harvester Using a Textile Coil Inductor

Abstract

-This research developed a textile coil inductor, in which conductive yarn was wound spirally onto textile, and produced an energy harvesting module utilizing a cylindrical compression coil spring structure to allow a permanent magnet to spin in the center hole of the coil inductor. The study confirmed through a pilot test that the voltage increased as the number of laminated layers of the coil inductor increased. Five subjects were tested in the energy harvesting measuring experiment after producing a sports shoe insole-mounted energy harvesting module. While the subjects executed sports motions such as walking and running at five given frequencies, the peak-to-peak voltage was measured by an oscilloscope and the accumulated energy voltage of the calculated rms voltage (Vrms) and the peak power (㎼) were derived. The output voltage increased as the frequency increased and the average Vp-p (V) of the five subjects was 0.53 V, the average peak power (㎼) was 0.289 ㎼, and the Vrms (V) was 0.065 V. This research is significant in that it suggests the possibility of an energy harvesting module based upon the textile coil inductor emerging from the former shoes' energy generator packaging method for heavy shoe types by developing a lightweight, flexible, and humanfriendly footgear module structure.

Wearable Human Motion and Heat Energy Harvesting System with Power Management

“…Since harvester parts are not meant to be enclosed in any rigid housing, there is no need to allocate any space for magnet movement like it is in traditional cylindrical coil construction [14], flat coils with magnetic suspension [34], or with the magnet moving through the coil [20]. Power density is considerably higher than for other electromagnetic harvesters summarized in [1], but most of them rely on inertia and thus have resonant frequency, which is high (e.g., P/V = 2,2 mW/cm 3 at f = 320 Hz).…”

“…Authors and other researchers have previously shown that it is possible to use flat spiralshaped coils [19,20] as inductors in electrodynamic harvesters and elements of electronic circuits. Another advantage of electromagnetic harvesters is their ability to work without direct contact between harvester elements, as it is necessary, for example, with piezoelectric harvesters; therefore, it is possible to implement them without changing shape, elasticity, and other mechanical properties of clothing [19].…”

A Review of Solar Energy Harvesting Electronic Textiles

“…Electromagnetic induction occurs when a conductive coil is placed within a varying magnetic field generating an electric current in the coil, and therefore this technique can be used to harvest energy from motion. Electromagnetic induction has been investigated for powering wearable devices [ 65 , 66 , 67 , 68 , 69 ], especially for shoes. An electromagnetic induction-based energy harvester normally has a permanent magnet at its core which is free to move inside of a tubular structure onto which conductive induction coils are mounted.…”

Boosting the efficiency of a footstep piezoelectric-stack energy harvester using the synchronized switch technology

“…Electromagnet systems have much higher efficiency in the mechanical-to-electrical energy transfer, while it usually involves coils and magnets (Cho et al, 2016;Ylli et al, 2015), which means a complicated and bulky mechanism is unavoidable. Piezoelectric materials can directly produce charge when stress is applied on it, and thus, piezoelectric energy harvesting (PEH) is widely studied (Xie and Cai, 2014) for some integrated working circumstances.…”