Browsing by Author "Huang, Cheng-Yeh"

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A highly efficient bead extraction technique with low bead number for digital microfluidic immunoassay
(2016-01)
Huang, Cheng-Yeh
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Tsai, Po-Yen
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Lee, I-Chin
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Hsu, Hsin-Yun
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Huang, Hong-Yuan
Here, we describe a technique to manipulate a low number of beads to achieve high washing efficiency with zero bead loss in the washing process of a digital microfluidic (DMF) immunoassay. Previously, two magnetic bead extraction methods were reported in the DMF platform: (1) single-side electrowetting method and (2) double-side electrowetting method. The first approach could provide high washing efficiency, but it required a large number of beads. The second approach could reduce the required number of beads, but it was inefficient where multiple washes were required. More importantly, bead loss during the washing process was unavoidable in both methods. Here, an improved double-side electrowetting method is proposed for bead extraction by utilizing a series of unequal electrodes. It is shown that, with proper electrode size ratio, only one wash step is required to achieve 98% washing rate without any bead loss at bead number less than 100 in a droplet. It allows using only about 25 magnetic beads in DMF immunoassay to increase the number of captured analytes on each bead effectively. In our human soluble tumor necrosis factor receptor I (sTNF-RI) model immunoassay, the experimental results show that, comparing to our previous results without using the proposed bead extraction technique, the immunoassay with low bead number significantly enhances the fluorescence signal to provide a better limit of detection (3.14 pg/ml) with smaller reagent volumes (200 nl) and shorter analysis time (<1 h). This improved bead extraction technique not only can be used in the DMF immunoassay but also has great potential to be used in any other bead-based DMF systems for different applications. (C) 2016 AIP Publishing LLC.
A Resettable, Wireless and Passive Fall-Down Recorder Using a Magnetic Droplet With an LC Circuit
(2016-02-01)
Huang, Cheng-Yeh
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Sun, Peng
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Lee, Meng-Shiue
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Wu, Sung-Yueh
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Shieh, Yi-Chueh
A fall-down recorder can record the happening of an object falling down during object delivery or transportation, even after the object is recovered to its initial state. Here, a resettable, wireless and passive fall-down recorder is proposed by integrating a droplet-based inertial force switch with the inductor-capacitor (LC) circuit for wireless signal transmission. A magnetic droplet is used in the switch with a converging microchannel to control the desired threshold acceleration. When the inertial force exceeds the designed threshold acceleration, the magnetic droplet will pass through the converging microchannel to a deep cavity to become a different state. By connecting the switch with the sensing LC circuit, the state of the recorder can be wirelessly identified through the LC resonant frequency. After triggering, this switch can be remotely reset to its initial state by an external magnet. A proper hydrophobic surface treatment is employed to facilitate the movement of the magnetic droplet and reduce the variation on the threshold acceleration. The capabilities, including switching, recording, wireless reading, and resetting of the proposed fall-down recorder, are successfully designed, fabricated, and verified with ten recording-reset tests.
AMPFLUID: Aggregation Magnified Post-Assay Fluorescence for Ultrasensitive Immunodetection on Digital Microfluidics
(2015-02-01)
Huang, Cheng-Yeh
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Shih, Po-Huai
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Tsai, Po-Yen
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Lee, I-Chin
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Hsu, Hsin-Yun
Several strategies are currently employed to enhance the detection limit of bead-based assays, but all these approaches improve the sensitivity by varying the assay procedures chemically or biologically. In previous digital microfluidic setups for bead-based immunoassay, the magnetic beads were suspended for detection. We investigated the effect of bead aggregation in such an immunoassay system and propose the aggregation magnified post-assay fluorescence for ultrasensitive immunodetection on digital microfluidics (AMPFLUID). The detection signal and sensitivity are further enhanced even at the post-assay stage without altering the original assay protocol on employing magnetically triggered post-assay aggregation of beads in a digital microfluidic setup followed by processing of the fluorescent signal. This method is shown to enhance the fluorescent signal with increased consistency and sensitivity after appropriate charge-coupled device (CCD) calibration. This method of on-chip detection allows the fulfilment of consumption of a volume at the nanoliter level and a limit of detection in the range picogram/mL. In our sTNF-RI model immunoassay, only 2.5 nL of sample is required; a detection limit 15 pg/mL is achieved. The decreased uncertainty of the measure is indicated by the error bars and coefficient of variation.
An EWOD-based micro diluter with high flexibility on dilution ratio
(2017-08-01)
Wang, Ying-Bin
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Huang, Jun-Hao
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Lee, Meng-Shiue
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Huang, Cheng-Yeh
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Huang, Cheng-Sheng
Dilution is a common procedure in biological and chemical analyses to perform tests at different concentrations. In previously reported micro diluters, although they could provide a wide dilution range, only limited dilution ratios were demonstrated, i.e. low flexibility in dilution ratio. Here, a droplet-based micro diluter with high flexibility on dilution ratio is proposed, fabricated, and tested. Through combination of five different electrode sizes using electrowetting-on-dielectric (EWOD) technique, the proposed micro diluter can provide 49 dilution ratios at dilution range from 1/2 to 1/50. Experimental results verify that different dilution ratios can be successfully generated, even at the most difficult low concentration range. Comparing to the design with equal electrode size in conventional EWOD-based microfluidic chip, the proposed design with unequal electrode sizes can reduce the operation steps to achieve high flexibility on dilution ratios efficiently.
Bead-Based Digital Microfluidic Immunoassay for IL-1 beta Detection in Embryo Culture Medium
(2017-01-01)
Tseng, Hsueh-Yang
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Jiang, Yi-Ting
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Huang, Cheng-Yeh
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Lee, Meng-Shiue
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Hsu, Wensyang
One of the challenges in IVF treatment is to improve the pregnancy rate of selective single embryo implantation. The concentration of IL-1 beta in embryo culture medium may help to predict pregnancy rate. Clinically, each embryo can only get small amount of sample size. However, the traditional immunoassay cannot detect biomarkers in such small sample sizes. Therefore, we combined immunoassay with the bead-based digital microfluidic chip. The chip has two advantages, low sample requirement and low detection limit. We established the mouse IL-1 beta calibration curve, confirm the Human Tubal Fluid (HTF) does not influence the test result and demonstrate that mouse IL-1 beta in clinical mouse embryo culture medium is positively correlate to cultured days. This device has a great potential for increasing IVF pregnancy rates.
Label-Free Separation and Sorting of Human Monocytes and T-cells by Electrowetting and Dielectrophoresis
(2013)
Huang, Cheng-Yeh
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Chiang, Min-Yu
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Fan, Shih-Kang
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Ghaemmaghami, Amir M.
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Hsu, Wensyang
We report a label-free separation and sorting approach based on electrowetting-on-dielectric (EWOD) and dielectrophoresis (DEP) to manipulate human monocyte (THP-1) and T-cell (Jurkat) lines in droplets without any impact on cell viability. In addition to separating cells, this device provides a platform to study cell-cell interactions and migration before the separation.
Signal Enhancement by Particle Concentration Using Dielectrophoresis in an Electrowetting-driven Droplet
(2012)
Chuo, Tsung-Min
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Hsu, Wensyang
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Huang, Cheng-Yeh
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Huang, Yu-Shan
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Chen, Yu-Tong
Signal Enhancement by Particle Concentration Using Dielectrophoresis in an Electrowetting-driven Droplet
(2012-01-01)
Chuo, Tsung-Min
;
Shih, Po-Huai
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Hsu, Wensyang
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Huang, Cheng-Yeh
;
Huang, Yu-Shan
This paper describes a new method for enhancing the fluorescence signal of a bead-based immunosensor in a digital microfluidic system by dielectrophoresis (DEP) force. A single droplet containing scattered polystyrene microbeads conjugated with fluorescent dye is first moved by electrowetting to 3-phase spiral electrodes. The fluorescent microbeads are then concentrated by DEP force at 145 VRMS over 100 kHz. It is shown that the proposed microfluidic chip can evidently enhance the fluorescent intensity even there are only very few fluorescent microbeads (10 to 100), where the droplet volume is only 6.25 nanoliter. The total operation time of the concentrating process is less than 3 minutes. The proposed signal enhancement method holds great potential for bead-based immunoassays to have better limit of detection with short analysis time and small sample volume.