Issue link: https://cp.revolio.com/i/763374
In recent years, progress has been made in the development and advancement of triboelectric energy harvesters, called triboelectric nanogenerators (TENG) [7]. A great number of materials found in the triboelectric series have been experimented with, as well as a number of surface morphologies, all in an effort to enhance the capabilities of these generators by maximizing charge. In addition to harvester design, advancements have enabled harvesting mechanical energy from vibration [11,12], human motion [12,13], the rotation of a tire [14,15], and flowing water [16]. Future work is expected to be applied to the development of self-powered sensors that are able to detect mechanical, chemical, temperature, and flow (wind and water) events [7]. An example of this type of sensor is a cylindrical triboelectric energy harvester built into the structure of a capsule endoscope, which is a small capsule that travels through and examines a person's digestive tract, removing the need for an invasive procedure. Creating a self-powered capsule endoscope that is not limited by battery power would overcome a serious hurdle for the current capsule endoscopes in use [17]. Design of Harvester & Package System Triboelectric energy harvesters rely on contact electrification to generate charge between the layers that possess a large difference in charge polarity. When these layers come into contact, the charge is able to transfer to the opposite layer and be collected by electrodes built into the harvester. Triboelectric energy harvesters require a few basic components: at least two triboelectric material layers, physical separation of these layers, and electrodes for the collection of the energy that moves between them, Fig. 1. Many different materials can be used in the structure of a triboelectric energy harvester, as long as they will develop charges of opposite polarity following physical contact with one another [17]. A triboelectric series is helpful in selecting two materials that will interact well with one another for triboelectric charge [9]. A triboelectric series is simply, "a list of materials empirically ordered according to their tendency to acquire positive or negative charges subsequent to mechanical contact [18], Fig. 2." The structure used for the harvester in this study is a single, vertical stack design, meaning that the layers are simply stacked atop one another, Fig. 3. The harvester designed and built is 55.88 cm x 35.56 cm x 8.50 mm, and contains six layers in total: B flute corrugate board, aluminum-coated PE with attached positive electrode, PTFE, cushion layer, aluminum coated PE with attached negative electrode, and B flute corrugate board. The two triboelectric materials used in the structure of this harvester are aluminum-coated PE and PTFE. The aluminum-coated PE is a 0.125mm polyester film, coated on one side with 99.7% Al, sourced from Advent Research Materials, Ltd (Oxford, England). The PTFE used is a skived, virgin, 3.18mm PTFE film sourced from CS Hyde Company (Lake Villa, Illinois). These materials have been used in combination for triboelectric charging ista views • December 2016 • www.ista.org Application of a Triboelectric Energy Harvester in Transport Packaging > CONTINUED FROM PAGE 19 20 Figure 1: The basic components of a triboelectric energy harvester. Figure 2: A basic triboelectric series. + more positive Glass Mica Polyaamind (Nylon 6,6) Rock salt (NaCl) Wool Fur Silica Silk Aluminum Poly(vinyl alcohol) (PVA) Poly(vinyl acetate) (PVAc) Paper Cotton Steel Wood Amber Poly(methl methacrylate) (PMMA) Copper Silver Gold Poly(ethylene terephthalate)(Mylar) Epoxy Resin Natural Rubber Polacrylonitrile (PAN) Poly(vinylidene chloride) (Saran) Polystyrene (PS) Polyethylene (PE) Polypropylene (PP) Poly(vinyl chloride)(PVC) Polytetrafluorethylene (Teflon, PTFE) more negative -