探討旅波介電泳對於介電溶液中粒子運動之影響

Abstract

本研究透過數學模型方法與實驗室晶片技術，分析微米級粒子在放射狀多相位電極作用下的運動現象。必揭示了粒子繞行電極旋轉之行為為一進動現象，且詳細分析了粒子在電場中的自轉與公轉，以及這些運動現象如何受到電場強度及粒子大小關係的影響。粒子以平行電極方向為自轉軸自轉，通過重力與傳統介電泳力提供角加速度，繞行電極中心公轉。當粒子在環形電極外圍時，電極間距寬於粒子大小，粒子主要受正旋度場加速；而在靠近中心電極時粒子大小大於電極間距，集中於電極表面的負旋度場主宰旋轉方向，開始出現與外圍相反的旋轉方向。 此外，研究進一步發現旅波介電泳力的本質是一種純旋度場，該力場可以持續傳輸能量提供粒子動能。在 3kHz 的螢光珠實驗中，我們觀測到粒子的動能持續增加至其旋轉速度超過每秒 30 幀的感光元件的捕捉頻率，我們應該以旋度場的角度去理解旅波介電泳現象。這種能量傳輸現象的發現，對於粒子動能的轉換提供了新的理解角度。 應用這一發現，我們成功地在實驗室晶片上展示了旋轉分離少量血球檢體的可行性，血球的分離效果在3kHz 時可以取得最好的應用。

This research delves into the dynamics of particles subjected to radial multi-phase electrode array, employing numerical simulations to elucidate the precessional movement of particles around electrodes. A detailed investigation into the particles' rotational and orbital behaviors under electric fields reveals the influence of electric field strength and particle size on these motions. Specifically, the study highlights the distinct rotational directions exhibited by particles when located at the electrode periphery versus near the electrode center, attributed to the differential field acceleration and reverse field dominance, respectively. A significant finding is the identification of the traveling wave dielectrophoretic force as a solenoidal field, allowing continuous energy transmission to augment the kinetic energy of particles. From the experiment with 3kHz fluorescent beads, we observed that the particles' motion speed continuously increased beyond the capture capability of the imaging sensors at 30 frames per second. The discovery provides a new perspective on the conversion of particle kinetic energy, and also reveals that traveling wave dielectrophoresis still has strong application potential compared to traditional dielectrophoresis. This insight paved the way for demonstrating blood cell rotational separation on a lab chip, with optimal separation effects achieved at 3kHz, showcasing potential applications in small sample diagnostics.