無閥式微型壓電幫浦的研製

Abstract

本文以實驗方式探討碟型壓電致動器泵動開放式無閥微幫浦的工作原理，將峰鳴片的電極等分成兩個半圓形作為壓電致動器，施以單相或雙相驅動，評估基本對稱(W00)與反對稱(W01)模態致動幫浦的流量。採用有限元素套裝軟體ANSYS分析蜂鳴片承受流體負載的共振頻率及模態，並以實驗及疊加法模擬雙相時諧致動所產生振動位移。實驗以Hasegawa et al (2005)的實驗架構為基礎，量測各個驅動頻率達成的流量。實驗結果顯示碟型致動器的共振頻率會因流體負載效應、導管與致動器的間距變小而降低，W00與W01模態致動幫浦的最大流量分別為133.13及9.63 ml/min，幫浦效率最高的驅動頻率略低於流體負載之蜂鳴片的共振頻率。蜂鳴片表面經疏水性處理後，流體負載的共振頻率反而低於未處理前，顯示以附加質量法模擬流體負載之結構共振頻率的論點仍有待進一步研究。

This thesis investigates experimentally the working principle of a valveless micropump with an open chamber actuated by a circular piezoelectric unimorph. Electrode of the piezoelectric buzzer is segmented into two semi-circular portions driven by singe-phase or dual-phase AC signals with a phase difference. The first symmetric mode, W00, and the first antisymmetric mode, W01, are excited to pump fluid inside the chamber. Resonant frequencies and corresponding vibration modes of the buzzer are calculated by using the finite element code ANSYS. Time-harmonic displacements of the unimorph induced by dual-phase signals are measured and simulated by superposition method. The experimental setup for measuring flow rate of the open-chamber micropump driven by a buzzer is after Hasegawa et al (2005). Experimental evidence indicates the resonant frequencies decrease due to fluid loading effect and by reducing the gap between leading tube and the buzzer. The maximum flow rate pumped by W00 mode is 133.13 ml/min and 9.63 ml/min by W01 mode. It occurs at the driving frequency slightly lower than the corresponding resonant frequency. The fluid loaded resonant frequencies for the buzzer whose backplane treated by hydrophobic process are lower than those without treatment. It results that a further formulation is needed to determine the resonant frequencies of fluid loaded structures exclusive of hypothesis of adding mass.