“Integration of Piezoelectric Power Harvesting and Synchronized Switching Interfaces” and “Multi-Input Single-Output (MISO) Energy Harvesting Interface Circuit”
PI: Prof. Wen-Jong Wu
Intel Champions: Dr. Lilly Huang
In the thriving era of internet, the internet connections are ready to connect things and machines to create intelligent life for convenience. The enormous amount of the de- vices may consume considerable extra power other than daily usages, which conflicts with the trend of power conservation. Hence the device should be supplied with an independent source with continuity.
In combination with the lower power limit requirements of the improved devices, the output of the MEMS power generators shall be collected in a sufficient way to realize applications. Hence, we should carefully design the interface circuits to eliminate the power loss and gain the best power output from the harvesting device. Due to the coupling between transducers and the interfacing circuits, it is very important to study both fields in the same time, so that the interaction between the effects can be precisely studied. In this way, the energy output can be more efficiently used and also transformed.
The current micro-energy harvester has its mechanical limits of material strength, resonance frequency, and operating bandwidth. The material strength is attributed to the substrate material and the piezoelectric material characteristic. Comparing to silicon, the stainless steel substrate that we use has already improved the sustainability of the device. It can provide a larger displacement and hence larger voltage output. On the other hand, the piezoelectric ceramic thick film also may crack from the large displacement under low frequencies. Our device is targeted to be around 100~120 Hz, for the usage of city power equipment.
As for the interfacing circuits, synchronized switching technique are often externally powered or requires high voltage for self-powering. The external power supply for the switching component often overrides the harvested power. Other than the regulating circuit, the complicated circuit within the self-powered switch also creates a remarkable component loss. Hence, the critical spec of the component loss factors should certainly be discussed to limit the power loss.
Additionally, the behavior of the ambient energy harvesting is random and the available converted power is in the range of mW, leading to the extremely low reliability for the power management circuits. Therefore, multiple harvesters from different sources not only enhance the reliability of the power management systems but al- so boost the available power.
When it comes to human motion of 0.5 to 1 Hz, we propose linear techniques featuring spiral or similar structures and nonlinear dynamic methods such as up conversion or bi-stable mechanisms for low frequency applications.
Members
Publications
Y. J. Wang et al., "Flexible patch composed of PZT thin-film on stainless steel foil for energy harvesting from low-frequency human motions", in Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2015, pp. 94353D.
W. Chuang et al., "Self-Sustain Wireless Sensor Module", in 2014 IEEE International Conference on Internet of Things (iThings), and IEEE Green Computing and Communications (GreenCom) and IEEE Cyber, Physical and Social Computing (CPSCom), pp. 288-291.
W. Wu et al., "Adjustable threshold-voltage in all-inkjet-printed organic thin film transistor using double-layer dielectric structures", Thin Solid Films, vol. 548, 2013, pp. 576-580.
