自潤滑固液摩擦奈米發電機之研究

Abstract

摩擦起電是一種常見的自然現象，當隨意的兩材料相互接近或摩擦後會產生接觸起電，而在2013年Zong Hong,Lin等人提出固液摩擦奈米發電機(Solid-Liquid Triboelectric Nanogenerator,S-L TENG)[1]，開啟了固液摩擦奈米發電機這塊新的領域，此裝置的發電方式是通過液滴與介電層的摩擦產生摩擦起電，使得電極受到靜電感應的影響產生電荷轉移，這樣的發電方式需要可以即時排斥液體的介電層且液滴的滑動速度與接觸面積很大程度上會影響發電效率，在大多數的研究中會製作出具有疏水或超疏水結構的表面，然而很少有研究探討將潤滑油注入表面來改善遲滯對於液滴與表面動態和輸出間的關係。 在此研究中利用旋塗的方法製作薄介電層，以具有指叉狀結構的ITO玻璃作為電極、PDMS作為摩擦層。本研究首先探討潤滑層對於輸出、表面與液滴的接觸影響，因PDMS具有疏水性與較大的遲滯，我們將PDMS 表面浸漬矽油池中降低接觸角滯後，同時維持摩擦發電能力，注入潤滑劑的表面能夠在最小傾斜角度下實現一致的液滴滑動和能量產生，而不會影響電力輸出，接著，我們測量液滴與表面滑動的速度與接觸面積變化，觀察出在滑動初期矽油層對輸出影響較重而後期則是滑動速度對輸出影響較大，並透過在連續液滴衝擊下的延長測試驗證了系統的耐用性，再來，我們觀察其表面的自修復能力以及測量自修復後的輸出，發現我們所製作的介電層較薄導致自修復後的輸出並未恢復到原始狀態，最後為了要提高摩擦電輸出性能，我們將高介電材料（例如 TiO2）摻入 PDMS 基質中，高介電常數奈米顆粒可與PDMS形成複合材料介電層，高介電常數可以增強介電層的極化能力使得電場更容易在介電層中建立穩定分布提升摩擦電壓，從而提高整體能量產生效率。

Triboelectrification is a common natural phenomenon. When two materials come into contact or rub against each other, contact electrification occurs. In 2013, Zong-Hong Lin et al. proposed the solid-liquid triboelectric nanogenerator (S-L TENG) [1], pioneering a new field in solid-liquid triboelectric nanogenerators. This device generates electricity through the friction between liquid droplets and a dielectric layer, resulting in triboelectric charging. The induced electrostatic effect on the electrodes causes charge transfer. This power generation method requires a dielectric layer capable of repelling liquids in real-time, and both the sliding speed and contact area of the droplets significantly impact power generation efficiency. Most studies have focused on fabricating surfaces with hydrophobic or superhydrophobic structures; however, few have explored the injection of lubricating oil into the surface to mitigate hysteresis and its effects on droplet dynamics and electrical output. In this study, a thin dielectric layer was fabricated using a spin-coating method, with interdigitated ITO glass as the electrode and PDMS as the triboelectric layer. First, we investigated the effect of the lubricant layer on electrical output and droplet-surface interactions. Due to the hydrophobicity and high hysteresis of PDMS, we immersed the PDMS surface in a silicone oil bath to reduce contact angle hysteresis while maintaining triboelectric power generation capability. The lubricated surface enabled consistent droplet motion and energy generation at minimal inclination angles without compromising electrical output. Subsequently, we measured changes in droplet sliding speed and contact area, observing that in the initial sliding phase, the silicone oil layer had a greater impact on output, whereas in the later phase, sliding speed played a more dominant role. The durability of the system was validated through extended testing under continuous droplet impact. Furthermore, we examined the self-healing ability of the surface and measured its output after self-healing. It was found that the thin dielectric layer resulted in incomplete recovery of the original output performance. Finally, to enhance triboelectric output performance, high-dielectric-constant materials (e.g., TiO₂) were incorporated into the PDMS matrix. The high-dielectric-constant nanoparticles formed a composite dielectric layer with PDMS, enhancing dielectric polarization and facilitating a more stable electric field distribution within the dielectric layer, thereby improving overall energy generation efficiency.