奈米摩擦發電機（triboelectric nanogenerator, TENG）可以將機械能轉換成電能，是目前新興的自供電技術。透過表面修飾技術使TENG的輸出性能提升，是目前最主流的方式之一。本研究開發出藉由靜電自組裝兩性離子trimethylglycine (M1)以及3-(ethyldimethyl-ammonio)propane-1-sulfonate (M2)做為聚二甲基矽氧烷（polydimethylsiloxane, PDMS）的界面修飾層，製作高性能且穩定的TENG。首先藉由鹼處理將PDMS表面改質成具有負電荷的表面（PDMS-O‐-H+），接著透過慢乾製程使兩性離子的正電基團與PDMS的負電荷形成靜電吸引力，並透過PAN鈍化PDMS-O‐-H+，讓PDMS-O‐-H+的穩定性提升，使兩性離子在表面達到最理想的排列。藉由這個策略，我們將結果延伸應用在大面積TENG，元件的開路電壓（open-circuit voltage, Voc）、短路電流（short-circuit current, Isc）分別達到728 V以及106.8 µA，其最高功率密度可達6.65 W/m2，且可同時點亮209顆LED燈。除此之外，我們的元件在連續二十萬次循環操作下，其輸出性能仍保持初始值的92.4%，顯示其出色的穩定性。此外，我們也將元件製作成可撓式元件，應用在穿戴式電子裝置來監測人體的移動，並做為自供電裝置來驅動濕度感測器。更重要的是，兩性離子不僅可以提升元件的電性輸出，還可以利用其中的正、負電基團分別捕捉陰離子以及陽離子的特性，應用於汗水感測，製備出自供電汗水感測器。這個成果顯示了表面改質技術的重要性，不但可以提升元件性能，甚至可以賦予元件汗水感測功能。本研究將加速TENG自供電裝置以及汗水感測技術的發展與進步。

Nowadays, triboelectric nanogenerator (TENG) that convert mechanical energy into electronic energy is a new self-powered technique. In order to improve the output performances of the TENG, the most common way is surface engineering. In this study, a strategy is demonstrated to develop high-performance and stable TENG by using electrostatic self-assembled zwitterions, trimethylglycine (M1) and 3-(ethyldimethyl-ammonio)-propane-1-sulfonate (M2), as surface modification layer.
First, the negative charge on polydimethylsiloxane (PDMS) surface created by base treatment, then through slow-dried procedure induces the electrostatic interaction between the positive charge from zwitterions and negative charge from PDMS. Additionally, the stability of PDMS-O‐-H+ was improved by incorporating the passivation layer of PAN, facilitating the most ideal molecular arrangement. By using this strategy, the output performances of the large-area TENG exhibits the open-circuit voltage (Voc) of 728 V, short-circuit current (Isc) of 106.8 µA, and the maximum power density of 6.65 W/m2, 209 light-emitting diodes (LEDs) lit up simultaneously. Moreover, the resulting TENG possesses excellent operating stability, maintaining the 92.4% of initial Voc after 200,000 operating cycles. Furthermore, we also manufacture the flexible TENG, and applying to human motion sensor and self-powered device. More importantly, the resulting TENG could even apply to self-powered sweat sensor by utilizing the negative- and positive-charged functional group on zwitterion that can capture positive and negative ions in sweat, respectively. This result demonstrates the importance of the surface engineering, that not only enhance the output performance, but also give the function of the sweat sensor. This study will accelerate the development of self-powered electronic device of TENG and sweat sensing technology.

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