Thermo-Harvested Autarkic Wireless Integrated Transmitter (THAWIT)

对于一般的物联网，特别是医疗传感器，需要低功率无线数据发射器。迄今为止，大多数这样的发射机需要电池或低效的射频（RF）收集。在THAWIT，我们希望研究和展示第一个无线数据发射器，它可以通过紧凑，集成，热电收集的方式提供。为了实现供应自给自足，我们必须应对以下挑战。发射机的功耗必须大大降低。此外，热电装置的功率密度必须增加。一个主要的挑战是在硅上集成的能力限制了可能的材料成分。我们希望开发出在7 K的中等温差下具有超过10 μW/mm 2的前沿功率密度的硅兼容收集元件。为了实现这一宏伟目标，我们严格优化了几何结构和材料组成。高的热电腿高度对于高输出功率密度是必要的，影响热电材料的光致抗蚀剂和沉积参数的选择。研究了p型热电脚的一种新工艺，以降低其导热系数。此外，我们开发了一种硅兼容的微型超级电容器作为能量缓冲器。为了与IFW的制造技术和设备兼容，我们通过高性能全固态叉指平面微型超级电容器实现了这一点。它是基于光刻图案溅射电极和固体电解质。考虑到节能损耗和2 mm 2的元件面积，CMOS发射器必须在10 μW或更低的直流功率下工作。为了实现这样的超低直流功率，我们研究了具有约0.1%的积极占空比、超快速斜坡上升和睡眠阶段的微小泄漏的直接调制振荡器。除了需要缓冲放大器的阻抗匹配天线之外，我们还考虑可以直接并入振荡器的LC谐振器中的电感天线。一个纺织品兼容的编织或印刷天线是专为演示。演示器应根据医疗植入物通信服务（MICS）进行操作。最终目标是显示400 MHz左右的数据传输，数据速率为1-10 kb/s，距离可达1米。THAWIT结合了Gabi Schierning，IFW在热电器件领域的互补能力，以及Frank Ellinger，TUD在低功率集成RF电路方面的互补能力。

For the internet of things in general and medical sensors in particular, low power wireless data transmitters are required. Up to date, most of such transmitters require batteries or inefficient radio frequency (RF) harvesting. In THAWIT, we want to investigate and demonstrate the first wireless data transmitter, which can be supplied by means of compact, integrated, thermo-electric harvesting. To allow supply-autarkic operation, we have to meet the following challenges. The power consumption of the transmitter must be massively reduced. Moreover, the power density of the thermoelectric devices must be increased. A major challenge is the capability for integration on silicon limiting the possible material compositions. We want to develop silicon-compatible harvesting elements with a leading-edge power density beyond 10 μW/mm2 at a moderate temperature difference of 7 K. To meet this ambitious goal, we rigorously optimise the geometry and material compositions. A high thermoelectric leg height is necessary for high output power density, affecting the choice of the photoresist and deposition parameters of the thermoelectric material. A new process for the p-type thermoelectric leg is researched to reduce the thermal conductivity. In addition, we develop a silicon-compatible micro-supercapacitor serving as energy buffer. To enable compatibility with the fabrication technology and equipment at IFW, we realize it by a high-performance all-solid-state interdigital in-plane micro-supercapacitor. It is based on photo-lithographically patterned sputtered electrodes and a solid electrolyte. Considering energy saving losses and component areas of 2 mm2, the CMOS transmitter must operate with a dc power of 10 μW or less. To enable such an ultra-low dc power, we study direct modulated oscillators with aggressive duty-cycling of around 0.1 %, ultra-fast ramp-up and miniaturized leakage in the sleep phases. In addition to impedance-matched antennas requiring buffer amplifiers, we consider also inductive antennas which can be directly incorporated in the LC-resonator of the oscillator. A textile-compatible woven or printed antenna is designed for the demonstrator. The demonstrator shall operate according to the medical implant communication service (MICS). The final goal is to show data transmission around 400 MHz with a data rate of 1-10 kb/s for distances of up to 1 meter. THAWIT combines the complementary competences of Gabi Schierning, IFW, in the area of thermoelectric devices, and Frank Ellinger, TUD regarding low power integrated RF circuits.