本論文提出一利用指叉電容式共振腔(Interdigital capacitor shape resonator, ICSR)應用於檢測人體之脈搏訊號，並進行雙點量測達到局部脈搏波速(Local pulse wave velocity)的量測。鑒於local PWV須高時間解析度，傳統頻率偏移量測需掃頻時間，無法達到高取樣率。因此提出利用振幅變化進行感測，並利用包絡檢波器(Envelope detector, ED)進行解調，可使取樣頻率大幅提升達到更高的時間解析度。除此之外在ICSR設計下相較於頻率偏移，振幅變化所感應之變化率更被大幅提升約89.77倍，且相較傳統CSRR在振幅變化上更有4.34倍的增強，進而可使脈搏波形更完整被量測出，提升計算脈搏傳導時間(Pulse transit time, PTT)之準確度。
由於系統之載波頻率為2.45 GHz之高頻訊號且脈搏訊號於心室收縮時會使訊號變化急遽，因此後方包絡檢波電路將需特別設計，否則時間特徵點無法被準確偵測。在此使用低中頻(low intermediate frequency, low IF)架構將訊號降頻進行數位包絡檢測，增加解調脈搏訊號之可靠度。不僅如此，更發現當使用混頻器降頻後非線性產生之高階諧振可使振幅變化達到倍率的放大。最後利用各個脈搏跳動訊號進行local PWV量測，一階IF之波對波變異率為11.75%，而3階IF則為7.82%，更為穩定。另外針對橈動脈上不同距離量測之結果，一階IF為2.965±0.721 (24.33%) m/s，而三階IF則為2.559±0.245 (9.59%) m/s，當變化率放大即可達到更靈敏穩定之量測。本論文提出一新穎且可行之微波脈搏波速量測系統。

In this thesis, a novel interdigital-capacitive-shaped resonator (ICSR) is proposed for wrist pulse signal detection, and local pulse wave velocities (PWV) can be measured by using microwave sensor from detecting pulses at two positions. An amplitude variation-based scheme is proposed for sensing, and an envelope detector (ED) can be applied for demodulation, so the sampling frequency can be greatly increased, implying a high time resolution. In addition, compared with the frequency deviation-based scheme, the sensitivity evaluated from the change ratio using the amplitude-based scheme is greatly improved by approximate 89.77 times, which enables the pulse waveform measurement more complete and more detailed. Therefore, the accuracy of the pulse transit time (PTT) measurement can be improved significantly. The low intermediate frequency (low IF) architecture is used to down-convert the signal for envelope detection in digital domain, which significantly increases the reliability of the pulse signal demodulation. Moreover, the higher order intermodulation (IM) components due to the nonlinearity can further boost the amplitude variation. The third-order IF can achieve nearly three-time amplification. In experiment, pulse beat signals are collected at adjacent positions separating at 30 to 90 mm on wrist for local PWV measurement. The variance of sampling feature time points from adjacent positions at first-order IF (fundamental IF) is 11.75% and can be further reduced to 7.82% at the third-order IF, implying a more stable and reliable system. In addition, the results of measurements on the radial artery at different distances shows that the PWV using the first-order IF is 2.965±0.721 (24.33%) m/s, and the PWV using the third-order IF is 2.559±0.245 (9.59%) m/s. It is verified that when the amplitude change ratio can be amplified, a more sensitive and stable measurement can be achieved. This novel and feasible microwave ICSR is demonstrated successfully for the local PWV measurement system.

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