開發具組織軟硬度辨識之壓電式軟性觸覺感測器

Development of Piezoelectric Flexible Tactile Sensor for Detection of Tissue Hardness

莊承鑫(Cheng-Hsin Chuag) ； 李讚修(Tsan-Hsiu Li) ； 呂昆峰(Kun-Feng Lu) ； 穆建良(Chien-Liang Mu)

《科儀新知》 197期 (2013/12) Pp. 36-45

摘要

依據衛生署統計，胃癌在台灣十大癌症死亡率排名第五。胃癌早期最常使用內視鏡影像進行檢測，然而，在胃裡有一種胃黏膜下腫瘤，主要發生於肌肉層，而表面胃黏膜毫無異狀，僅邊緣平緩隆起，常誤認為正常黏膜皺壁，目前診斷上主要以內視鏡超音波來檢測，由於設備昂貴，且僅限醫療中心才有。因此，本研究提出一種新穎的量測方法，基於結構化電極之軟性壓電式觸覺感測器的概念，利用感測器內層結構材料及外層包覆材料之楊氏模數不同，致使接觸軟硬組織時呈現電壓比值之差異性，來達到即時診斷的能力。為模擬黏膜下腫瘤型態，利用仿人體的黏膜與腫瘤之雙層結構，分別進行數值模擬與實驗量測，由模擬結果顯示，感測器對於量測黏膜下較為軟性之彈性體的辨識能力較高。實驗方面，為了驗證觸覺感測器是否能辨識黏膜下組織軟硬度，我們選用兩種薄膜作為上層結構，一為與生物組織軟硬程度相似的PDMS薄膜，二為直接採用豬胃所擷取下來的黏膜，分別針對下層4種不同硬度等級之彈性體進行量測，實驗結果得知，所開發之觸覺感測器具有辨識黏膜下組織軟硬的能力。未來將感測器微小化，並安裝於內視鏡附件前端，以建立定量化資料庫及模組系統，進行即時觀察黏膜下組織之硬度值，輔助醫師在診斷上的便利與方便性。

並列摘要

Detecting the mechanical characteristic of tissues is a highly effective means of distinguishing between a cancerous lump and healthy tissues during minimally invasive surgery (MIS). Gastric submucosal tumors are difficult to diagnosis by endoscope due to tumors covered by normal gastric mucosa tissue. This presents a novel miniaturized tactile sensor for differentiating the hardness of elastomer under a gastric mucosa of pig. The flexible tactile sensor consists of two patterned flexible print circuits (FPCs) sandwiching a polymer piezoelectric film (PVDF) and a small steel ball embedded in a soft material (PDMS) on the FPC surface. Owing to the stiffness difference between a steel ball and PDMS material, the uneven stress distribution on piezoelectric film can be induced and varied with contact objects. Therefore, the ratio of voltage outputs between the inner and outer electrodes on the piezoelectric film can differentiate between the mechanical characteristics of a contact object. Experimental results indicate that the voltage ratio increases with the Young's modulus of elastomer from 1 to 3 MPa. Additionally, the voltage ratio not only depends on elastomer Young's modulus but also affects by the magnitude of normal force app lied on tactile sensor. Consequently, capable of differentiating between soft tissues, the tactile sensor is thus highly promising for integration with a medical device for minimally invasive surgery.