生物啟發性之超細微質量與超弱力感測技術

Abstract

生物啟發性之感測技術，就是模仿生物的感測技術，是近十年來很熱門的研究課題。這類仿生技術需要跨領域研究團隊的合作，從嚴謹的基礎研究中激發創新。我們龍蝦團隊從研究細菌線毛的生物結構力學，首次發現第三型線毛不但展現了橢圓形截面、類螺旋形結構的主幹，而且這樣特殊的奈米結構使得線毛的機械特性展現三個階段的伸縮行為。為此，我們提出一個理論模型，充分解釋線毛的結構與機械特性之間的關係。

從嚴謹的生物力學實驗過程中，我們發現線毛是絕佳的天然奈米彈簧。這激發我們根據基礎的振盪共振器原理，設計一套微粒子□線毛的超細微質量感測系統。當一個病毒黏附在微粒子上時，我們透過了分辨出這套振盪系統的共振頻率之變化，即可解析出該病毒的質量。理論上，這套超細微質量感測系統的質量解析度約為10^-15 g，和單一病毒的質量相當。

在力學理論模型的發展過程中，我們發現線毛在第二階段伸縮的機制，相當於一顆微粒子在一個雙捕捉光中進行位能狀態的躍遷。這激發我們利用雷射鑷夾技術，建構一套超弱力感測系統。我們透過觀測微粒子在兩個位能井之間的躍遷頻率變化，即可量測到超微弱的水流沖刷力。實驗結果顯示，這套超弱力感測系統的力精確度約為10^-15 N，超越了現有的力學感測技術所面臨的熱擾限制。

從基礎研究細菌線毛的結構力學，到開發生物啟發性之超細微質量與超弱力感測技術，這是一套完整的研發策略，而我們期待這將會是個激發創新的仿生研發範本。

Bio-inspired techniques, the so-called biomimetic techniques, are popular issues in recent ten years. The development of these novel techniques requires the interdisciplinary cooperation and is frequently inspired from fundamental researches. From a study on structural mechanics of bacterial fimbriae, our Lobster team firstly found that type 3 fimbriae exhibit elliptical cross sections and helix-like structures. The special nano structures enable the fimbriae to exhibit a typical three-phase stretching and contracting behavior. To explain the unique behavior, we have proposed a model for the relationship between the fimbrial structure and elasticity.

According to the mechanical experiments of fimbriae, we found that a fimbria could be an excellent nano spring in a resonant oscillator. The discovery inspired us to design an ultrasmall mass sensing system composed of a bead-fimbria element. By detecting change in resonant frequency of the sensing system, we can determine whether a virus of 10^-15 g in mass is adhered to the bead.

In addition, our model inspired us to design an ultraweak force sensing system, and we demonstrated that a bead restricted in a bistable optial trap could hop between two energy states. By monitoring change in the transition rates of the bead hopping between the two states, a flow force of 10^-15 N imposed on this system was measured. The femto-Newton-level resolution of the technique is beyond the thermal noise limit.

From the fundamental research of fimbriae to the invention of the two bio-inspired sensing techniques, the research project provides a complete strategy. We expect that the strategy will be a research model for biomimetic techniques.