臺灣博碩士論文加值系統

(i)一般由基材帶電官能基極化引起直流電滲流幫浦在電極處會產生氣泡，電壓大於1伏特時，也可能產生其他電化學反應，限制直流電滲流幫浦生產力，並削減它相對於機械式注射筒或氣壓幫浦而言可攜帶的便利性。藉由誘導極化包埋電極上之高頻(>100 kHz)交流電滲流幫浦能避免氣泡產生，但是需要精巧電極設計產生淨流動。本論文提出利用高頻交流電場對介電材質表面電容充電誘導極化槽道，在具幾何特異性之槽道角產生誘導電滲流，提升帶電效果來達到有效率混合和推進效果的方法。交流電滲流誘導表面介電極化和帶相反電荷離子電雙層製造出大於1伏特之有效zeta電位和約為1 cm/s之滑移速度，比直流電滲流情況大一個至兩個數量級以上。由於場洩漏(field leakage)的緣故，介電材料於尖角處極化並不一致，不均勻滑移速度造成激烈混合漩渦。在3 mm直徑容槽中，溶質僅藉單純擴散進行混合需要一小時以上才能有效混合，具漩渦情況下則僅需30秒。本高輸出量交流電滲流幫浦優點包括電極上氣泡不易產生，誘導極化產生處不只是在電極，而是整個槽道表面，極化現象和高頻率下電場平方成線性關係，電極放在欲推動流體容槽之外，溶液推動量每秒最大可達約1 micro-liter。
(ii)使用毫米大小具導電性並可使離子通過奈米孔洞的小顆粒，在出口端可將電雙層中帶異性電離子達到瞬時百萬倍濃縮，濃縮過程僅需1秒。此現象歸因於特殊的帶異性電離子遮蔽的動力學，其可將朝向出口端一半的表面電場收斂。結果表面傳導流將上游對流電渗流異性電離子流注入噴射半球端的點狀閘產生超級濃縮。被濃縮的帶異性電離子往群體電解質溶液噴射時，被吸引之帶同性電荷離子，一起噴射出去，產生帶同性電荷離子濃縮。濃縮效果受電解質溶液產生的電雙層厚度與小顆粒粒徑以及小顆粒孔洞大小影響。
(iii)本實驗室曾提出利用導電離子交換樹酯顆粒非線性電動漩渦流結合其在低頻率交流電場下(0.1 Hz, 133 V/cm)電泳運動產生混沌(chaotic)流線充分攪動基質分子，以降低溶液中基質和被包埋酵素擴散距離而加速消化速率的混合機制。在5分鐘的消化時間內，催化反應速率提升了大約30倍，再現性約為15%；若是不加入離子交換顆粒，則提供有限攪拌，速率僅提升9倍，再現性約為30%。速率提升和實驗室先前染料分子在容槽中擴散近百倍的混合增進倍率相比低了釵h；推測是樹酯顆粒和溶膠凝膠顆粒間摩擦力，造成樹酯顆粒無法順暢移動所致。實驗設計在槽道中加入染料分子以鑑別溶膠凝膠顆粒存在於容槽情況下，外加電場和離子交換顆粒對染料分子擴散性的影響。在有或無離子交換顆粒的情況下，染料擴散性分別提升了30與8倍。在有溶膠凝膠顆粒下，染料擴散性由將近100倍降為30倍左右，染料擴散性和催化反應速率的增進倍率相當一致，證實為樹酯顆粒和溶膠凝膠顆粒間摩擦力，造成樹酯顆粒無法順暢移動所致。
(iv)在毛細管電泳方法中，利用鎖相放大器輸出頻率100 Hz以上脈衝電壓，可以增強分析物訊號並降低閃動雜訊，獲得有效光學訊號品質改善。由管壁電雙層中帶電離子滑移帶動的電渗流為一種動量擴散黏度流(viscous flow)，動量傳遞至管中央時需要一段前置時間，此時間之倒數即為脈衝電壓之頻率上限。當頻率超過上限時，動量傳遞時間小於前置時間，將無法帶動管中央流體的移動；藉由求解微管道中隨時間變化的運動擴散方程式，發現前置時間和需擴散的特徵距離以及槽道形狀有關。對具相同特徵距離的圓柱狀毛細管和平板狀槽道而言，前者前置時間大約為後者的一半。由前置時間估計，當頻率上限為可有效抑制閃動雜訊100 Hz時，平板槽道半寬最大為100 micro-meter，圓柱狀槽道半徑則為140 micro-meter。槽道設計尺寸建議隨頻率增加而減小；使得由管壁傳導之電滲流能夠完整傳遞至管中央，以達到毛細管中良好的分離效果。

An efficient mixing and pumping device using ac electro-osmosis driven by field- induced polarization at high frequency by non-contact electrodes is developed. The device consists of three circular reservoirs (3 mm in diameter) connected by two 1 × 1 mm channels and electrodes are outside of the mixing and pumping unit. The mechanism uses the external field to charge the surface capacitively. The charging and mixing are enhanced at tailor-designed channel corners by exploiting the high normal fields at geometric singularities. The induced channel surface dielectric polarization and the resulting electric counter-ion double layer produce an effective Zeta potential in excess of 1V and an electro-osmotic slip velocity at 1 cm/s and larger, both 1-2 order of magnitude larger than dc electro-osmosis. The polarization is non-uniform at the corners due to field leakage to the dielectric substrate and the inhomogeneous slip velocity produces intense mixing vortices that effectively homogenize solutes in 30 s, in contrast to hour-long mixing by pure diffusion. This ac induced electro-osmotic pump has a net flow with a maximum pumping throughput of 1 micro-liter/s toward the side channel. The non-contact electrodes used at high frequency can minimize electrode bubble generation and contaminants from electrochemical reactions at voltages beyond 1 V for electrolytes. Polarization over the entire channel surface, quadratic scaling with respect to the field and high voltage at high frequency without electrode bubble generation are the reasons why the current pump is superior to earlier dc and ac EO pumps.
A transient 10^6-fold concentration of double-layer counterions by a high-intensity electric field is demonstrated at the exit pole of a mm-sized conducting nanoporous granule that permits ion permeation. The phenomenon is attributed to a unique counterion screening dynamics that transforms half of the surface field into a converging one toward the ejecting pole. The surface conduction flux then funnels a large upstream electro-osmotic convective counterion flux into the injecting hemisphere toward the zero-dimensional gate of the ejecting hemisphere to produce the super concentration. As the concentrated counterion is ejected into the electroneutral bulk electrolyte, it attracts co-ions and produce a corresponding concentration of the co-ions.
A novel microstirring strategy is applied to accelerate the digestion rate of the substrate catalyzed by sol-gel encapsulated enzyme. An ac nonlinear electrokinetic vortex flow is used to stir the solution in a microfluidic reaction chamber to reduce the diffusion length between the immobilized enzyme and substrate in the solution. High-intensity nonlinear electroosmotic microvortices are generated around a small (1.2 mm) conductive ion exchange granule when ac electric fields (133 V/cm) are applied. Coupling between these microvortices and the on-and-off electrophoretic motion of the granule in low frequency (0.1 Hz) ac fields produces chaotic stream lines to stir substrate molecules sufficiently. Within a 5-min digestion period, the catalytic reaction rate of immobilized trypsin increases almost 30-fold with adequate reproducibility (15%) due to sufficient stirring action through the introduction of the nonlinear electrokinetic vortices. In contrast, low-frequency ac electroosmotic flow without the granule, provides limited stirring action and increases the reaction rate approximately 9-fold with barely acceptable reproducibility (30%). Dye molecules are used to characterize the increases in solute diffusivity in the reaction reservoir in which sol-gel particles are placed, with and without the presence of granule, and compared with the static case. The solute diffusivity enhancement data show respective increases of ~30 and ~8 times, with and without the presence of granule. These numbers are consistent with the ratios of the enhanced reaction rate.
In capillary electrophoresis, effective optical signal quality improvement is obtained when high frequency (>100 Hz) external pulse fields modulate analyte velocities with synchronous lock-in detection. However, the pulse frequency is constrained under a critical value corresponding to the time required for the bulk viscous flow, which arises due to viscous momentum diffusion from the electro-osmotic slip in the Debye layer, to reach steady-state. By solving the momentum diffusion equation for transient bulk flow in the micro-channel, we show that this set-in time to steady-state and hence, the upper limit for the pulse frequency is dependent on the characteristic diffusion length scale and the channel geometry; for cylindrical capillaries, the set-in time is one half of that for rectangular slot channels. From the estimation of the set-in time and hence the upper frequency modulation limit, we propose that the half width/the radii of planar/cylindrical channels does not exceed 100/140 micro-meter such that there is a finite working bandwidth range above 100 Hz and below the upper limit in order for flicker noise to be effectively suppressed.

1. 緒論 1
1.1 前言 1
1.2 微流體簡介 1
1.3 線性電滲流 2
1.4 非線性電滲流 5
1.4.1濃度極化理論 5
1.4.2 球形導電離子選擇顆粒在強電場下造成的極化現象 8
1.4.3 與線性電滲流比較 9
1.5 研究動機 9
1.6 文章架構 10
2. 利用非接觸式外加電極誘導交流電滲流混合與推動現象 12
2.1 前言 12
2.2 研究方法 18
2.2.1 藥品 18
2.2.2 藥品或溶液配製 19
2.2.3 實驗器材與儀器設備 19
2.2.4 微流體混合與推動裝置 20
2.2.5 電場提供 23
2.2.6 實驗步驟 23
2.3結果與討論 24
2.3.1 混合效率評估 24
2.3.2 混合效率與電場相關性 30
2.3.3 推進速率計算 30
2.3.4 推進速度與電場相關性 32
2.4 結論 33
3. 利用離子交換樹酯達成電雙層臨界點動態超級濃縮 36
3.1前言 36
3.2研究方法 40
3.2.1藥品 40
3.2.2藥品或溶液配製 40
3.2.3 實驗器材與儀器設備 41
3.2.4 微流體濃縮裝置 43
3.2.5 電場提供 45
3.2.6 陽離子交換樹酯顆粒活化 45
3.2.7 實驗步驟 45
3.3結果與討論 46
3.3.1 螢光濃度校正曲線 46
3.3.2 濃縮情形 48
3.3.3 濃縮區域等高線分佈圖 50
3.3.4 離子穿透性與電解質溶液濃度效應 51
3.3.5 陰離子交換樹酯濃縮應用 53
3.3.6 理論 54
3.4結論 58
4. 以染料分子擴散性實驗解釋非線性交流電動漩渦流促進溶膠凝膠包埋酵素催化活性實驗結果 60
4.1 前言 60
4.2 研究方法 63
4.2.1 藥品 63
4.2.2 藥品或溶液配製 64
4.2.3 實驗器材與儀器設備 64
4.2.4 微流體反應裝置 65
4.2.5 離子交換樹酯活化與選擇 66
4.2.6 電場提供 68
4.2.7 溶膠凝膠的製備 68
4.2.8染料擴散實驗 68
4.3結果與討論 69
4.3.1 酵素催化實驗 69
4.3.2 染料擴散性實驗 71
4.3.3 混沌漩渦流影響 74
4.4 結論 75
5. 圓柱狀微管道電泳分析物速度調控之脈衝電場頻率限制 77
5.1 前言 77
5.2 理論模型 80
5.2.1公式的推導 80
5.2.2 分析解(Analytical solution) 83
5.2.3 達穩定態電滲流所需前置時間的估算 85
5.3 結果與討論 86
5.3.1 前置時間與頻率調控上限 86
5.3.2 非對稱槽道幾何形狀延伸 87
5.3.3 可抑制閃動雜訊的最大槽道尺寸 87
5.4 結論 88
6. 未來展望 89
7. 參考文獻 90

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