A D V A N C E D M A T E R I A L S & P R O C E S S E S | A P R I L 2 0 2 3 3 8 iTSSe TSS iTSSe TSS FEATURE 6 The Internet of Things (IoT) connects devices and systems that exchange data acquired from actuators and sensors in machines and other physical objects. he aim of enabling these devices and systems to communicate independently of human interaction is to facilitate data exchange, enhance efficiency, and quality of life[1]. IoT devices have a wide range of applications: They can be used at home to study and predict human activities and to actively modify the environment for predicted needs such as adjusting temperature and lighting to minimize energy consumption. IoT can be used in cities to monitor air quality, ensure efficient lighting, and in agriculture to monitor soil conditions and optimize watering and pesticide spraying[2-6]. Figure 1 shows some potential applications of the IoT. As IoT promotes more independence from human interaction, the need for more sensors and communication add-ons stimulates a higher demand for decentralized energy sources[4,5,8]. Consequently, efforts are made to develop more energy-efficient components by miniaturization[9]. Moreover, the development of IoT and the rising awareness about global warming and cleaner energy sources[10] paves the path for the development of more creative and sustainable methods to harvest energy from the environment such as electromagnetic radiation (light and RF waves), thermal gradients, and mechanical motion[2,5,8]. Successful attempts to extract power from environmental energy have been made. Piezoelectric[9,10], and more recently triboelectric[11] and fluidic electric[12] materials were developed to take advantage of vibration, friction, and water-flow-induced ion distribution to generate electricity. MEET TECHNOLOGY Moisture-electric energy transformation (MEET) technology is being developed to further expand the utilization of environmental energy sources like thermal power, wind power, hydropower, and solar energy. The goal of the development of such a technology is to extract power from environmental moisture with as few conversion processes as possible to satisfy the ever-growing demand for new and more portable energy sources required by IoT[13]. The materials used in the manufacturing of MEET devices are prepared and disposed in such a way that a gradient of H+ ions is established through their thickness upon exposure to water or moisture. To guarantee such a gradient, hydrogen-releasing functional groups must be present through the thickness of the MEET device, commonly oxygen-rich carboxyl (-COOH) and hydroxyl groups (-OH)[13]. Water absorption occurs in the hydrophilic oxygen-rich parts of the MEET device. Water molecules cause the regional solvation of the oxygen-containing groups, weakening thebonds between the oxygen Oδ- and the hydrogen Hδ+ in the carboxyl or hydroxyl groups and releasing a hydrogen ion or proton (H+). The negatively charged oxygen atoms O- remain stationary COLD SPRAY AIDS DEVELOPMENT OF DECENTRALIZED ENERGY HARVESTERS The use of cold spray to produce moisture-electric energy transformation devices results in a greener process. Bertrand Jodoin, FASM,* and Amir Daoud University of Ottawa, Canada *Member of ASM International Fig. 1 — An overview of potential IoT applications[7].
RkJQdWJsaXNoZXIy MTYyMzk3NQ==