適用於體熱供電之低功率無線生理訊號監控系統

A Body-Heat-Powered Low-Power Wireless Physiological Signal Monitoring System

翁博軒(Po-Shuan Weng)

指導教授 ： 呂良鴻

國立臺灣大學/電機資訊學院/電子工程學研究所/博士(2015年)

https://doi.org/10.6342/NTU.2015.10215

摘要

無所不在的熱能往往是以能源轉換過程中的損耗在我們的日常生活中悄悄現身，並且可以溫差和熱流的形式存在於綠色能源擷取應用。大型的汽車及工業廢熱回收即是提高轉換效率並降低汙染的絕佳例子。近年隨著半導體的製程的微小化亦使得利用小型熱電轉換元件進行小規模的體熱能源擷取的可行性大增。而近期所興起的穿戴式電子裝置更是提供了一個相當好的發揮平台以迎接零電池的願景時代來臨。而這對近年來需求量與日俱增的遠距醫療生理訊號監控裝置的應用上更是一大福音，在長時間的配戴需求下，除了免去繁複的電池更換，減輕病人的負擔並降低其潛在的危險性更是提高使用意願的關鍵。在能源供給條件相對嚴苛且相關研究仍在發展階段的前提下，這三個概念及應用導向的趨勢將透過此論文所提出的系統從最基礎的鍊路預算分析進行統整與實現。
為能克服能源擷取系統中高頻切換雜訊干擾源及能源轉換效率不佳的限制，提出一系列的電路解決方案。在第三章中，透過三級步階啟動的電路架構，使得直流升壓電路能同時達成超低電壓的啟動以及穩態時的高轉換效率。在第四章中，基於超取樣三角積分訊號量化特性搭配電源的穩壓，傳統的生理訊號前端接收電路的高解析度特性得以被完整保留並可直接提供一位元的數位串流資料輸出；不僅如此，所提出的主動式電阻置換技巧在不影響電路特性的前提下更可大幅減少所需的晶片面積。在第五章中，藉由三角積分數位調變切換式電源轉換電路搭配數位式的功率放大器以及適當的電源控管介面，使得無線傳輸介面的能源轉換效率及雜訊特性在系統整合後仍可以有效的維持並大幅提高製程的可攜性。第六章則針對前述的各個子電路進行系統整合並有完整電性驗證及實際應用情境的展示。

關鍵字

體熱供電 ； 超低電壓啟動 ； 低功耗 ； 生理訊號監控 ； 超取樣 ； 高效率無線傳輸

並列摘要

Omnipresent thermal energy is one of the most eco-friendly energy sources. It is often presented as losses during other energy conversion processes and is applicable for energy harvesting in terms of a temperature gradient or a heat flow in our daily life. One important application with large-scale energy harvesting is automotive or industrial waste heat recovery. Recovering waste heat not only improves the overall efficiency but reduces the pollutions as well. Another emerging application with small-scale energy harvesting is the body heat which establishes a temperature gradient between the human body and the ambient. With recent advances in semiconductor fabrication technology, miniaturized thermoelectric generator (TEG) devices have been successfully fabricated for small-scale energy harvesting, promoting a promising application scenario of batteryless wearable electronics along with the recent development, which is also beneficial for the explosive proliferation of the demand on physiological signal monitoring devices for telehealth applications. It is believed that batteryless wearable devices in terms of safety and comfort essentially attract the intention of long-term usage on patients. Under the premise of rather stringent energy constraint, integration and realization of these concepts as well as application-oriented future trends are presented initializing from the fundamental link budget analyses.
In this thesis, in order to alleviate limitations imposed by the high-frequency switching noises and relatively low energy conversion efficiencies in energy-harvesting systems, several circuit topologies are developed for thermoelectric energy-harvesting applications. In chapter 3, a 3-stage stepping-up architecture is proposed to achieve an ultra-low startup voltage while maintaining high steady-state conversion efficiencies as well for the dc-dc boost converter. In chapter 4, based on the oversampling ΔΣ signal processing technique and supply regulation, the resolution of the frontend circuit for physiological signal monitoring is completely preserved with a direct 1-bit digitized serial data output. In addition, significant area reduction with proposed active resistors can also be achieved without degrading the performance. In chapter 5, by utilizing the proposed ΔΣ-modulated switching power supply with a digital power amplifier and appropriate power management interface, the wireless transmitter is capable of maintaining the energy conversion efficiency and noise performance effectively after the system integration. Corresponding system integration of the proposed building blocks is introduced in chapter 6 including comprehensive electrical characterization and verification along with practical thermoelectric demonstration.

並列關鍵字

body-heat-powered ； ultra-low-voltage startup ； low-power ； physiological signal monitoring ； oversampling ； high-efficiency wireless transmission

參考文獻

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[4] “Thomas Johann Seebeck,” Wikipedia: the Free Encyclopedia, Sep. 23, 2014 [Online]. Available: http://en.wikipedia.org/wiki/Thomas_Johann_Seebeck [Dec. 12, 2014].