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應機械工程學院邀請，美國田納西大學(The University of Tennessee, Knoxville)吳杰副教授于2017年6月19~21日訪問我校，并做微尺度傳感與檢測、微流控芯片技術等微機電系統領域的系列學術報告。

報告（一）

報告題目：A Passive and Wireless Lab-on-a-Film for Disposable and Wearable Microfluidics

報告時間：2017 年 6月19日（星期一）上午9:00-10:00

報告地點：紅橋校區北院機械樓211會議室

報告人：吳杰（Jayne Jie Wu）副教授（美國田納西大學）

內容簡介：

A wirelessly powered and controlled biased-AC electroosmotic (biased-ACEO) lab-on-a-film (LOF) is presented here for particle and fluid manipulation. Amplitude modulation (AM) and inductive coupling are used for wireless transmission of low frequency signals required for excitation of biased-ACEO effects employed by the LOF for microfluidic functions. The LOF consists of a receiving coil (for receiving inductively transmitted high frequency signals), surface mounted devices (for recovering a low frequency AC signal) and an array of interdigitated electrodes (IDE, for excitation of biased-ACEO effects). Unlike existing wireless lab-on-a-chip devices that have cumbersome set-ups, require high voltages and perform only one microfluidic function, the presented LOF has a compact and flexible structure, works at very low voltage ranges, and can perform several microfluidic operations corresponding to a wirelessly-controlled voltage. When the level of the demodulated signal over the IDE is about 0.7 V, the IDE performs particle enrichment over designated electrodes. The IDE functions as an active mixer at about 2 V; and as a pump when the voltage reaches 3 V. The LOF is prototyped rapidly on a flexible substrate at low cost using inexpensive benchtop equipment with an overall dimension of 10 × 20 mm2. Though the electrode definition is limited to micro-scales, the LOF prototype has successfully demonstrated desired microfluidic functions. In addition to inductive transmission of low frequency signals, the printed circuit board-based LOF device offers a low cost and effective solution for using small, flexible microfluidic systems in nontraditional clinical diagnostic tools, disposable devices and heath care settings.

報告（二）

報告題目：Thermally biased AC electrokinetic pumping effect for Lab-on-a-chip based delivery of biofluids

報告時間：2017 年 6月20日（星期二）下午14:30-15:30

報告地點：紅橋校區北院機械樓211會議室

報告人：吳杰（Jayne Jie Wu）副教授（美國田納西大學）

內容簡介：

One major motivation for microfluidic research is to develop point of care diagnostic tools, which often demands a solution for chip-scale pumping that is of low cost, small size and light weight. Electrokinetics has been extensively studied for disposable pumping since only electrodes are needed to induce microflows. However, it encounters difficulties with conductive biofluids because of the associated high salt content. In electrokinetic pumps, electrodes are in direct contact with fluid, so high salt content will compress the electric double layer that is essential to electroosmostic flows. Alternating current electrothermal (ACET) effect is the only electrokinetic method found viable for biofluid actuation. While high frequency (>10 kHz) operation can suppress electrochemical reactions, electrical potential that could be applied over biofluids is still limited within several volts due to risk of electrolysis or impedance mismatch. Since ACET flow velocity has a quartic dependence on the voltage, ACET flows would be rather slow if electric field alone is used for actuation. This work studies the effect of a thermal bias on enhancing AC electrokinetic pumping. With proper imposition of external thermal gradients, significant improvement in flow velocity has been demonstrated by numerical simulation and preliminary experiments. Both showed that with 4 Vrms at 100 kHz, flow velocity increased from ~10 μm/s when there was no thermal biasing to ~112 μm/s when a heat flux was applied.

報告（三）

報告題目：Interactions of Electrical Fields with Fluids: Biotechnological Applications

報告時間：2017 年 6月21日（星期三）上午9:00-10:00

報告地點：紅橋校區北院MBA樓一樓報告廳

報告人：吳杰（Jayne Jie Wu）副教授（美國田納西大學）

內容簡介：

A microfluidic chip should have following functions: mixing, pumping, concentration step to assist detection, etc., as shown schematically here. As device dimension scales down, pressure driven flow becomes increasingly inefficient due to high surface-volume ratio. In contrast, electrokinetics is gaining popularity as a microfluidic actuation mechanism, due to its no moving parts and easy implementation. Traditional electrokinetic pumping requires applying high DC voltage across the microchannel, and the electric field drives the mobile charges at the fluid/channel interface (i.e. electroosmosis) to transport fluid. High voltage causes bubble generation and pH gradients from electrochemical reactions. To minimize these adverse effects, AC electrokinetics (ACEK) has emerged recently for on-chip pumping and particle manipulation for its low voltage operation.

ACEK investigates the behavior of particles in fluid and the motion of electrolytic fluids when they are subjected to AC electrical fields.  Charges are induced in the bulk of the fluids where there is an interface (e.g. electroosmosis) or gradients in fluid attributes (e.g. electrothermal effect). Because the electric fields and induced charges in fluid change polarity simultaneously, steady (not oscillatory) fluid motion can be generated in ACEK.  There are mainly three types of ACEK phenomena, dielectrophresis (studied since 1991), AC electroosmosis (since 1999, our group initiated “biased ACEO”) and AC electrothermal effect (our group is the first to have developed ACEK micropumps). ACEO is mainly effective for low-conductivity fluid (e.g. water), thus limiting its application in lab-chips. We have developed capabilities for conductive fluids, making an important step towards practical EK devices.

ACEK can also manipulate micro/nano particles in the fluid, which include DNA, protein molecules, virus, bacteria, plant and animal cells, and inorganic particles. To detect low concentration bioparticles, a concentration step is necessary to increase particle count to a critical mass at the detection sites. ACEK is the only known on-chip method to collect particles in a short time. My group prototyped a first in-situ microcantilever particle trap (experimented on 200nm to 1µm particles), and we are extending it to protein and DNA concentrating.

報告人簡介：

吳杰（Jayne Jie Wu），1999年和2004年分別獲中國科學院應用物理和美國圣母大學(Notre Dame)電子工程學的博士學位，現任美國田納西大學副教授，主要從事交流電動力學(Alternating Current Electrokinetics)與微流控芯片(Microfluidics, Lab-on-a-chip)技術的基礎與應用研究，目前兼任田納西大學及時診斷與納米生物傳感技術中心(Initiative for PON/POC Nanobiosensing)主任。獨立主持田納西大學微系統課題組，是國際上最早開展微流體交流電熱(Alternating Current Electrothermal)效應理論和應用研究的幾個研究組之一。

所主持的美國國家科學基金項目“非對稱極化交流電滲實驗室芯片研究”獲Career獎，課題組專注于微尺度顆粒的介電泳(dielectrophoresis, DEP)技術，生物流體的智能傳感與控制、微驅動與微執行器件的開發等研究。近五年來，吳杰教授課題組致力于解決開發新型微流控生物傳感器所面臨的基礎科學問題。目前在生物傳感器與微機電系統領域的主流期刊Biosensors and Bioelectronics, Microfluidics and Nanofluidics, Biomicrofluidics, Biomedical Microdevice, Sensors and actuators等發表SCI學術論文60余篇，總被引用1300余次，H因子為21。兼任IEEE可穿戴生物力學傳感與系統學會高級會員，Austin Journal of Biosensors and Bioelectronics，Journal of Mechanics in Medicine and Biology等期刊編委。