Energy Harvesting Triboelectric Nano-Generators for the Internet-of-Things

物联网和5G技术等下一代技术正在塑造中，通过创建一个数字连接的世界来提高人们的生活水平，在这个世界中，生产力、健康和通信将得到极大改善。这涉及将传感器、智能电路和微型电子设备集成到我们周围的日常物体中，包括人体、服装、建筑物、车辆和街道等。由于低功率电子和物联网技术的进步，此类系统变得越来越可行，然而，为这些电子产品提供所需的复杂性、灵活性、移动性和自供电能力仍然是现代的关键挑战之一。从可自由获得的环境机械能源(如人体运动、风能、波能和机器振动)中获取电能已被证明是满足这些能源和性能要求的可行方法。摩擦电纳米发电机(TENG)是为自主物联网应用提供潜在能源的主要候选之一。这些设备已经显示出从环境来源捕获废旧机械能量的能力，并且很容易产生几瓦的输出功率，据报道转换效率很高。然而，对Tengs的电磁行为以及它们的确切工作方式的了解在过去一直很匮乏。因此，结构、材料和运动参数与输出功率之间的关系还没有得到充分的研究。这导致了非优化的Teng架构，其输出功率相对较低、瞬时和不规则，以及Teng和输出应用之间的阻抗不匹配。这些问题降低了Teng的输出功率，并显著降低了其效率。最近，我们引入了距离相关电场(DDEF)模型，这是第一个完全描述TEGS工作原理的解析理论模型，它使用麦克斯韦方程。该模型已被证明能够准确地预测不同Teng工作模式的输出行为，并已成功地应用于简单平面Teng的优化策略，显著减少了上述大多数问题。在拟议的项目中，我们将使用DDEF模型来优化Teng的材料、器件和运动参数，以开发用于物联网应用的自主能量收集器，如健康传感器、无线通信网络、便携式和可穿戴电子产品。我们将首先评估物联网设备的能源需求，并设计具有适当效率的Teng，以从环境来源捕获能量。然后对这些器件进行微调，以获得理想的大小、形状和材料类型，以适应应用，同时提供最佳的电场分布，从而增加功率输出。我们将使用常见的、低成本和柔性的摩擦电聚合物(如尼龙、聚酯)作为Teng层，并进一步使用可扩展的低成本制造技术。将进行基于纳米技术的表面改进，以进一步提高这些设备的效率。我们的模拟和计算结果表明，与未优化的器件相比，建议的改进将使输出功率提高约100%。为了确保不间断的正常供电，我们将整合许多具有计算相差的Teng单元，这将导致接近DC的输出电流。最后，我们将结合电源管理电路和能量存储单元(如超级电容器和柔性电池)以及Teng to IoT模块，组装出完全集成的自给式IoT设备。

Next generation technologies, such as the IoT and 5G technology, are shaping to enhance the standard of life of people by creating a digitally connected world, in which the productivity, health, and communication will be vastly improved. This involves integrating sensors, intelligent circuits and miniature electronic devices into day to day objects around us, including the human body, clothing, buildings, vehicles and streets etc. Such systems become increasingly feasible due to the advancements in low-power electronics and IoT technologies, however, powering these electronics with the required complexity, flexibility, mobility and self-powered capabilities remains one of the key challenges in the modern era. Scavenging power from freely available ambient mechanical energy sources, such as human motion, wind, wave energy and machine vibrations, has been proven to be a viable approach to fulfil such energy and performance requirements.The triboelectric Nanogenerator (TENG) is one of the leading candidates to emerge as a potential energy source for powering autonomous IoT applications. These devices have shown the capability of capturing waste mechanical energy from ambient sources and easily producing a few Watts of output power, with high conversion efficiencies reported. However, knowledge of the electromagnetic behaviour of TENGs and the exact way they operate has been lacking in the past. Consequently, the relationship between the structural, material and motion parameters with the output power has not been adequately studied. This has resulted in non-optimised TENG architectures which suffer from relatively low, instantaneous and irregular output power, along with an impedance mismatch between the TENG and the output applications. Such issues decrease the output power of the TENG and significantly reduce its efficiency. This in turn associates with numerous other issues such as elevated cost, higher carbon footprint, larger device size and unreliable power supply.Recently, we introduced the distance-dependent electric field (DDEF) model, the first analytical theoretical model to fully describe the working principles of TENGs, using Maxwell's equations. This model has been proven to accurately predict the output behaviour of different TENG working modes and has been successfully applied to develop optimisation strategies for simple planar TENGs, significantly reducing most issues described above.In the proposed project, we will use the DDEF model to optimise material, device and motion parameters of TENGs to develop autonomous energy harvesters for IoT applications such as health sensors, wireless communication networks, portable and wearable electronics. We will first assess the energy requirements of IoT devices and design TENGs with suitable efficiencies to capture that energy from ambient sources. These devices are then finetuned to obtain the ideal size, shape, and material type, which will fit the applications while providing optimum electric field distribution, resulting in increased power outputs. We will use commonly available, low cost and flexible triboelectric polymers (eg: nylon, PET) as TENG layers, and further use scalable low-cost manufacturing techniques. Nanotechnology based surface improvements will be conducted to further improve the efficiency of these devices. The suggested improvements will increase the output power by about 100% compared to a non-optimised device, as evident from our simulation and calculation results. To ensure a non-interrupted regular power supply, we will integrate many TENG units with calculated phase differences, which would result in a near DC output current. Finally, we will combine the power management circuits and energy storage units (eg: supercapacitors and flexible batteries) along with the TENG to the IoT module, to assemble the fully integrated self-powered IoT devices.