應用於內鏡觸診應用之噴墨列印石墨烯壓阻式觸覺感測器

Abstract

微創手術(MIS)中，對於讓醫師獲得即時術中生理資訊如組織硬度、結構等器官訊息，以利手術器械之使用是極為重要之技術發展。舉例來說，因為腫瘤的硬度較高，力回饋可以幫助醫師從健康的組織中辨別癌症腫瘤。近年研究專注於以雙彈簧單元所設計之微機電(MEMS)型觸覺感測器並置於手術器械之上，藉由應力、應變分布的比值偵測組織軟硬差異。然而，沒有一種機制能在實際觸診中正確地反應組織的機械性質與提供深層的器官結構感測。本篇論文提出透過可自由移動之柱狀結構連結兩個噴墨列印石墨烯壓阻式感測器，藉由同時感測力及位移輸出實現微創手術所需之觸覺感測器。上方感測單元之形變能夠透過柱狀結構傳達給下方感測單元，並使下方感測單元壓入組織。當組織受到相應的形變量，下方感測單元能夠藉由力回饋所造成之相應的形變量判別組織的硬度差異。實驗結果顯示在該感測器可分別呈現出2.1mN豬脂肪和5.3mN肌肉組織力回饋。2.5倍的力回饋差異不僅能顯示肌肉為較硬組織之外，亦展示在與現有技術相比之下，該觸覺感測器可讓醫生於內視鏡手術中更能直觀地感知組織硬度之差異。

In minimally invasive surgery (MIS), force feedback is critical for doctors to real-time access surgical tool status and organ information such as tissue structure and hardness, etc.. For instance, the feedback can help doctors to identify a cancerous lump within healthy tissues due to its larger hardness. Recent studies focused on implementing MEMS-typed tactile sensors typically designed with a two-spring element for detecting hardness difference based on a feedback stress or strain ratio in MIS. None of them, however, can truly reflect the real mechanical property of tissues and provide deep sensing capability on organs for real palpation practice. The sensor proposed in the thesis comprises two inkjet printed piezoresistive graphene-based sensing elements back-to-back linked by a freely standing rod for force and displacement detection, respectively. The loaded upper element will result in a deformation directly transferred to press the bottom element into the tissue by the rod. With the same deformation inside the tissues, the bottom element cans, therefore, sense the hardness difference via the feedback force from the tissues. Experimental result shows the sensor can exhibit 2.1 and 5.3mN force feedback from the fat and muscle tissues of pig respectively, while it is pressed with the same 100m displacement to the tissues. ~2.5 times difference in force feedback indicates not only the muscle is harder but also doctors can intuitively percept hardness difference during endosurgery in comparison with the prior arts.