本研究利用灰階式的光學圖形投影在具有光敏功能之生物晶片，進而誘發出非均勻交流電場，使生物粒子受電場極化產生介電泳力(dielectrophoresis force, DEP)，以此物理現象結合微流體系統，將生物粒子自動且連續地濃縮或分離。光誘發式的介電泳(Light-induced DEP, LIDEP)晶片具有較簡易的製程步驟與即時操控功能；相較傳統的LIDEP圖形，灰階式的LIDEP(gray-scale LIDEP, GS-LIDEP)圖形所能誘發出相當廣泛的電場梯度，可有效操控散佈在微管道中的生物粒子；此外以傳統金屬電極較難以達到灰階圖形的電場作用效果。為了達到自動分離與廣泛且更有效操控生物粒子，本研究設計出多階的GS-LIDEP圖形並結合微流體系統，使粒子產生一垂直於流體方向的側向移動之介電泳力，可達到自動且連續的分離效果。在0.6 ul/min的流體速率下，以36 Vp-p、10 kHz之交流電訊號，成功地以正介電泳力引導Candida cells，該引導效率可達90%；在40 Vp-p、10 kHz之交流電下，2 um latex呈現正介電泳力而10 um呈現負介電泳力，便以此現象分離不同粒徑大小粒子，該分離效率分別可達88%與81%。在正介電泳力的作用下，由於血球的遷移率較低於E. faecium；因此，在40 Vp-p、10 kHz的交流電場下，以動態的光誘發圖形可成功分離E. faecium與血球。

This article presents a gray-scale light-induced dielectrophoresis (GS-LIDEP) method that induces the lateral displacements normal to the through-flow for continuous and passive separation of microparticles. In general, DEP force only can affect the particles within very local areas, because the electric field exponentially decays by the distance away from the electrodes. Unlike with conventional LIDEP, a broad-range electrical field gradient can easily be created by GS-pattern illumination, which induces DEP forces with two directions for continuous separation of particles to their specific sub-channels. Candia albicans populations were effectively guided to the specific outlet with the efficiency of 90 % to increase the sample concentration below the flow rate of 0.6 ul/min. 2 um and 10 um polystyrene particles can also be passively and well separated using the multi-step GS-pattern through positive and negative DEP forces, respectively, under an applied voltage of 36 Vp-p at the frequency of 10 kHz. DEP force that is capable of working on the entire area of the microchannel, and thus the mix of particles with different size can be passively and continuously separated toward the opposite directions by the both positive and negative GS-LIDEP forces. Dynamic pattern was also used to selectively concentrate bacteria from blood cells based on their different mobilities related to the moving speed under an applied voltage of 40 Vp-p, at a frequency of 10 kHz. This simple, low cost and flexible separation/manipulation platform could be very promising for many applications, such as in-field detections/pretreatments.

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