Name: a versatile kit based on digital microfluidics droplet actuation for science education
Uploaded: 2021-04-26T13:30:00
Description: Watch this Scientific Journal Video about A Versatile Kit Based on Digital Microfluidics Droplet Actuation for Science Education at JoVE.com

Y. T. Y. would like to acknowledge funding support from the Ministry of Science and Technology under grant numbers MOST 107-2621-M-007-001-MY3 and National Tsing Hua University under grant number 109Q2702E1. Mark Kurban from Edanz Group (https://en-author-services.edanzgroup.com/ac) edited a draft of this manuscript.

1) Assembling the digital microfluidics kit
<ol>
	<li>Solder the surface mount resistors, transistors, and light-emitting diodes onto the PCB board according to the schematics in Figure 1b.</li>
	<li>Connect the output of the high-voltage power supply board to the PCB board with soldered components (Figure 2 and Supplementary Figure 1).</li>
	<li>Connect the battery to the voltage booster board to boost the voltage from 6 V to 12 V (<strong cl...

<ol>
	<li>Convery, N., Gadegaard, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=30+years+of+microfluidics.">30 years of microfluidics.</a> Micro and Nano Engineering. 2, 76-91 (2019).</li><li>Rackus, D. G., Ridel-Kruse, I. H., Pamme, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Learning+on+a+chip:+Microfluidics+for+formal+and+informal+science+education.">Learning on a chip: Microfluidics for formal and informal science education.</a> Biomicrofluidics. 13, 041501 (2019).</li><li>Legge, C. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemistry+under+the+microscope-Lab+on+a+chip+technologies.">Chemistry under the microscope-Lab on a chip technologies.</a> Journal of Chemical Education. 79, 173 (2002).</li><li>Fintschenko, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Education:+a+modular+approach+to+microfluidics+in+the+teaching+laboratory.">Education: a modular approach to microfluidics in the teaching laboratory.</a> Lab On A Chip. 11, 3394 (2011).</li><li>Mugele, F., Baret, J. -. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrowetting:+from+basics+to+applications.">Electrowetting: from basics to applications.</a> Journal of Physics: Condensed Matter. 17, 705-774 (2005).</li><li>Lippmann, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Relations+entre+les+phenomenes+electriques+et+capillary.">Relations entre les phenomenes electriques et capillary.</a> Ann. Chim. Phys. 6, 494 (1875).</li><li>Berge, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrocapillarite+et+mouillge+de+films+isolant+par+l'eau.">Electrocapillarite et mouillge de films isolant par l'eau.</a> C. R. Acad. Sci. II. 317, 157 (1993).</li><li>Pollack, M. G., Fair, R. B., Shenderov, A. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrowetting-based+actuation+of+liquid+droplets+for+microfluidics+applications.">Electrowetting-based actuation of liquid droplets for microfluidics applications.</a> Applied Physics Letters. 77, 1725 (2000).</li><li>Lee, J., Kim, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface-tension-driven+microactuation+based+on+continuous+electrowetting.">Surface-tension-driven microactuation based on continuous electrowetting.</a> Journal of Microelectromechanical Systems. 9 (2), 171 (2000).</li><li>Choi, K., Ng, A. H. C., Fobel, R., Wheeler, A. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Digital+Microfluidics.">Digital Microfluidics.</a> Annual Review of Analalytical Chemistry. 5, 413-440 (2012).</li><li>Jebrail, M. J., Wheeler, A. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Let's+get+digital:+digitizing+chemical+biology+with+microfluidics.">Let's get digital: digitizing chemical biology with microfluidics.</a> Current Opinion in Chemical Biology. 14, 574-581 (2000).</li><li>Pollack, M. G., Pamula, V. K., Srinivasan, V., Eckhardt, A. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=2011.+Applications+of+electrowetting-based+digital+microfluidics+in+clinical+diagnostics.">2011. Applications of electrowetting-based digital microfluidics in clinical diagnostics.</a> Expert Review of Molecular Diagnostics. 11, 393-407 (2011).</li><li>Abdelgawad, M., Wheeler, A. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+prototyping+in+copper+substrates+for+digital+microfluidics.">Rapid prototyping in copper substrates for digital microfluidics.</a> Advanced Materials. 19 (1), 133-137 (2007).</li><li>Abdelgawad, M., Wheeler, A. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Low-cost,+rapid-prototyping+of+digital+microfluidics+devices.">Low-cost, rapid-prototyping of digital microfluidics devices.</a> Microfluidics and Nanofluidics. 4, 349-355 (2008).</li><li>Fobel, R., Fobel, C., Wheeler, A. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=DropBot:+an+open-source+digital+microfluidic+control+system+with+precise+control+of+electrostatic+driving+force+and+instantaneous+drop+velocity+measurement.">DropBot: an open-source digital microfluidic control system with precise control of electrostatic driving force and instantaneous drop velocity measurement.</a> Applied Physics Letters. 102, 193513 (2013).</li><li>Yafia, M., Ahmadi, A., Hoorfar, M., Najjaran, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultra-portable+smartphone+controlled+integrated+digital+microfluidic+system+in+a+3D-printed+modular+assembly.">Ultra-portable smartphone controlled integrated digital microfluidic system in a 3D-printed modular assembly.</a> Micromachines. 6 (9), 1289-1305 (2015).</li><li>Alistar, M., Gaudenz, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=OpenDrop:+an+integrated+do-it-yourself+platform+for+personal+use+of+biochips.">OpenDrop: an integrated do-it-yourself platform for personal use of biochips.</a> Bioengineering. 4 (2), 45 (2017).</li><li>Khan, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Luminol-based+chemiluminescent+signals:+clinical+and+non-clinical+application+and+future+uses.">Luminol-based chemiluminescent signals: clinical and non-clinical application and future uses.</a> Applied Biochemistry and Biotechnology. 173 (2), 333-355 (2014).</li><li>Agresti, J. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrahigh-throughput+screening+in+drop-based+microfluidics+for+directed+evolution.">Ultrahigh-throughput screening in drop-based microfluidics for directed evolution.</a> Proceedings of the National Academy of Sciences of the United States of America. 107 (9), 4004-4009 (2010).</li><li>. Microfluidics Available from: <a target="_blank" href="https://microfluidics.utoronto.ca/dropbot/">https://microfluidics.utoronto.ca/dropbot/</a> (2020)</li><li>Busnel, J. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evaluation+of+capillary+isoelectric+focusing+in+glycerol-water+media+with+a+view+to+hydrophobic+protein+applications.">Evaluation of capillary isoelectric focusing in glycerol-water media with a view to hydrophobic protein applications.</a> Electrophoresis. 26, 3369-3379 (2005).</li><li>Chatterjee, D., Shepherd, H., Garrell, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electromechanical+model+for+actuating+liquids+in+a+two+plate+droplet+microfluidic+device.">Electromechanical model for actuating liquids in a two plate droplet microfluidic device.</a> Lab On A Chip. 9, 1219-1229 (2009).</li></ol>

The procedure described here allows the reader to assemble and test a working EWOD system for droplet actuation and gain hands-on experience with microfluidics. We intentionally avoid expensive components and chemical samples. Currently, one kit can be constructedfor ~$130 with the most expensive component being optical color glass for fluorescent imaging and microcontroller excluding the custom acrylic enclosure (Supplementary Table 1). For such a cost, a fluorescent imaging capability and an active hum...

Microfluidics is a highly interdisciplinary field combing physics, chemistry, biology, and engineering for the manipulation of small volume of liquids ranging from femtoliter to microliters1. Microfluidics is also a very broad and active field; a Web of Science search returns nearly 20,000 publications and yet there is insufficient literature and review papers on the usage of microfluidics as educational tool2. There are two insightful, albeit outdated review articles by Legge and Fintschenko3,4. Legge introduces educators to the idea of a lab on a chip3. Fintschenko pointed out the role of microfluidics teaching lab in Science Technology Engineering Mathematics (STEM) education and simplified the philosophies into &#34;teach microfluidics&#34; and &#34;use microfluidics&#34;4. A more recent review by Rackus, Ridel-Kruse and Pamme in 2019 points out that in addition to being interdisciplinary in nature, microfluidics is also a very hands-on subject2. The hands-on activity related to the practice of microfluidics lends students to inquiry-based learning and makes it an engaging tool for science communication and outreach. Microfluidics indeed offers much potential for science education in both formal and informal settings and is also an ideal &#34;tool&#34; to enthuse and educate the general public about the interdisciplinary aspect of modern sciences.
Examples such as low-cost microchannel devices, paper microfluidics, and digital microfluidics are ideal tools for educational purposes. Among these platforms, digital microfluidics remains esoteric and peer-reviewed reports based on digital microfluidics are lacking2. Here we propose to use digital microfluidics as an educational tool for several reasons. First, digital microfluidics is very distinct from microchannel-based paradigm because it is based on manipulation of the droplets and usage of the droplets as discrete microvessels. Second, droplets are manipulated on relatively generic electrode-array platforms so digital microfluidics can be intimately coupled with microelectronics. Users can leverage on an extended set of electronic components, now highly accessible for do-it-yourself applications to electronically interface with droplets. Hence, we argue that digital microfluidics can let students to experience these unique aspects and be open-minded not overly to stick to microchannel-based low Reynold number microfluidics1.
Briefly, the field of digital microfluidics is largely based on the electrowetting phenomena, which was first described by Gabriel Lippmann5,6. The recent developments were initiated by Berge in the early 1990s7. His key contribution is the idea of introducing a thin insulator to separate the conductive liquid from metallic electrodes to eliminate the problem of electrolysis. This idea has been termed as electrowetting on dielectric (EWOD). Subsequently, the digital microfluidics was popularized by several pioneering researchers8,9. Now a comprehensive list of applications for example, in clinical diagnostics, chemistry and biology, has been proven on digital microfluidics10,11,12 and, therefore, plenty of examples are available for an educational setting. In particular, along the line of low cost, do-it-yourself digital microfluidics, Abdelgawad and Wheeler have previously reported low-cost, rapid prototyping of digital microfluidics13,14. Fobel et al., has also reported DropBot as an open source digital microfluidic control system15. Yafia et al., also reported a portable digital microfluidics based on 3D printed parts and smaller phone16. Alistar and Gaudenz have also developed the battery powered OpenDrop platform, which is based on the field effect transistor array and dc actuation17.
Here, we present a digital microfluidics educational kit based on commercially sourced printed circuit board (PCB) that allows the user to assemble and get hands-on experience with digital microfluidics (Figure 1). Fee-for-service to create PCB from digital design files is widely available, and hence we think it is a viable low-cost solution for education provided that digital design files can be shared. Meticulous choice of components and system design is made to simplify the assembly process and make an interface with the user&#39;s intuitive. Hence, a one-plate configuration is used instead of a two-plate configuration to avoid the need for a top plate. Both the components and the test chemicals need to be easily available. For example, food wrap from the supermarket is used as the insulator in our kit.
To prove feasibility of our kit, we suggest a specific chemistry experiment based on chemiluminescence of luminol and provide the protocol. The hope is that visual observation of chemiluminescence can enthuse and excite students. Luminol is a chemical that exhibits a blue glow when mixed with an oxidizing agent such as H2O2 and is typically used in forensics to detect blood18. In our laboratory setting, potassium ferricyanide serves as the catalyst. Luminol reacts with the hydroxide ion and forms a dianion. The dianion subsequently reacts with oxygen from hydrogen peroxide to form 5-aminophthalic acid with electrons in an excited state, and relaxation of electrons from the excited state to the ground state results in photons visible as a burst of blue light.
We also report a fluorescent imaging experiment with a smart phone to demonstrate the integration of a light-emitting diode (LED) as an excitation light source. Finally, droplet evaporation is a problem in microfluidics but is rarely being addressed. (A 1 &#956;L of water droplet is lost within 1 h from an open substrate3.) We use an atomizer based on a high-frequency piezo transducer to convert water into fine mist. This creates a humidified environment to prevent droplet evaporation and demonstrates long-term (~1 h) droplet actuation.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/61978/61978fig01.jpg" /> 
Figure 1: Schematics of EWOD set up. (a) A microcontroller is used to provide a control sequence to the EWOD electrode. Also, the humidity is controlled. (b) Schematics of PCB layout. Electrodes, LED for fluorescent imaging, resistor, and field effect transistors (FET) are labeled. Scale bar of 1 cm is also shown.&#160;<a href="https://www.jove.com/files/ftp_upload/61978/61978fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/61978/61978fig02.jpg" /> 
Figure 2: Top view of the kit. Microcontroller board, high voltage supply board, EWOD PCB, humidity sensor, and atomizer are labeled.&#160;<a href="https://www.jove.com/files/ftp_upload/61978/61978fig02large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Acrylic enclosure</td>
			<td>LOCAL vendor</td>
			<td></td>
			<td>23cm x 20.5 cm x 6cm</td>
		</tr>
		<tr>
			<td>Ardunion Uno</td>
			<td>Arduino</td>
			<td>UNO</td>
			<td>microcontroller board</td>
		</tr>
		<tr>
			<td>acetic acid</td>
			<td>Sigma Alrich</td>
			<td>695092-100ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Breadboard</td>
			<td>MCIGICM</td>
			<td>400tie</td>
			<td>4 cm x 7 cm, 400 Points Solderless Breadboard, a pack of 4</td>
		</tr>
		<tr>
			<td>BSP89 H6327 Infineon MOSFET&#160;</td>
			<td>Mouser</td>
			<td>726-BSP89H6327</td>
			<td>drain soure breakdown voltage 240V,on resistance 4.2 ohm</td>
		</tr>
		<tr>
			<td>citrid acid</td>
			<td>sigma Alrich</td>
			<td>251275-100G</td>
			<td></td>
		</tr>
		<tr>
			<td>Color glass filter&#160;</td>
			<td>Thorlabs</td>
			<td>FGL 530</td>
			<td>color glass filter for fluorescent imaging</td>
		</tr>
		<tr>
			<td>DHT11 temperature &#38; humidity sensor</td>
			<td>adafruit</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Digital multimeter&#160;</td>
			<td>Fluke</td>
			<td>17B</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorescein isothiocyanate isomer I</td>
			<td>sigma Alrich</td>
			<td>F7250-50MG</td>
			<td>50 mg price, fluorescent imaging</td>
		</tr>
		<tr>
			<td>Glycerol</td>
			<td>Sigma Alrich</td>
			<td>G9012-500ML</td>
			<td></td>
		</tr>
		<tr>
			<td>High voltage power supply for Nixe tube</td>
			<td>Vaorwne</td>
			<td>NCH6100HV</td>
			<td>High voltage power max dc 235V</td>
		</tr>
		<tr>
			<td>LM2596 voltage booster circuit</td>
			<td></td>
			<td></td>
			<td>boost voltage from 5V to 12 V</td>
		</tr>
		<tr>
			<td>Luminol</td>
			<td>Sigma Alrich</td>
			<td>123072-5G</td>
			<td>5 g for $110</td>
		</tr>
		<tr>
			<td>Pippet</td>
			<td>Thermal Fisher</td>
			<td></td>
			<td>1- 10 ul</td>
		</tr>
		<tr>
			<td>Printed circuit board&#160;</td>
			<td>Local vender</td>
			<td></td>
			<td>10 piece for $60</td>
		</tr>
		<tr>
			<td>Plastic food wrap</td>
			<td>Kirkland</td>
			<td>Stretch-tite&#160;</td>
			<td>food wrap Plastic food wrap</td>
		</tr>
		<tr>
			<td>Potassium ferricynide</td>
			<td>Merck</td>
			<td>104982</td>
			<td>1 kg</td>
		</tr>
		<tr>
			<td>1N Potassium hydroxide solution (1 mol/l)&#160;</td>
			<td>Scharlau&#160;</td>
			<td></td>
			<td>1 Liter</td>
		</tr>
		<tr>
			<td>Clear Office tape 3mm</td>
			<td>3M Scotch</td>
			<td></td>
			<td>semi-transparent, used as diffuser for illumination</td>
		</tr>
		<tr>
			<td>salt</td>
			<td>Great Value Iodized Salt</td>
			<td></td>
			<td>6 oz for $7 salt from supermarket</td>
		</tr>
		<tr>
			<td>Silicone oil (5Cst)</td>
			<td>Sigma Alrich</td>
			<td>317667-250ML</td>
			<td>top hydrophobic layer &#38; filling layer between electrode and insulator</td>
		</tr>
		<tr>
			<td>sucrose</td>
			<td></td>
			<td></td>
			<td>table sugar&#160; from any supermarket, 6 dollar per pound</td>
		</tr>
		<tr>
			<td>Surface mount blue LED</td>
			<td>oznium</td>
			<td>3528</td>
			<td>Oznium 20 Pieces of PLCC-2 Surface Mount LEDs, 3528 Size SMD SMT LED - Blue</td>
		</tr>
		<tr>
			<td>Surface mount resistor 180k Ohm</td>
			<td>Balance World Inc</td>
			<td></td>
			<td>3mm x 6 mm 1watt</td>
		</tr>
		<tr>
			<td>Surface mount resistor 510Ohm</td>
			<td>Balance World Inc</td>
			<td></td>
			<td>bias resistor for LED, 3mmx6mm 1watt</td>
		</tr>
		<tr>
			<td>Water atomizer</td>
			<td>Grove&#160;</td>
			<td></td>
			<td>operating frequency 100 kHz&#160; supply votage 5V max 2W&#160; The kit comes with ultrasonic transducer</td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td>high voltage transistor</td>
		</tr>
	</tbody>
</table>

a versatile kit based on digital microfluidics droplet actuation for science education

This paper describes an educational kit based on digital microfluidics. A protocol for luminol-based chemiluminescence experiment is reported as a specific example. It also has fluorescent imaging capability and closed humidified enclosure based on an ultrasonic atomizer to prevent evaporation. The kit can be assembled within a short period of time and with minimal training in electronics and soldering. The kit allows both undergraduate/graduate students and enthusiasts to obtain hands-on experience in microfluidics in an intuitive way and be trained to gain familiarity with digital microfluidics.

The droplet actuation is recorded with a smart phone. Representative results for chemiluminescence and fluorescent imaging are displayed in Figure 3 and Figure 4. For the chemiluminescence experiment, the droplet of 10 &#956;L ferricyanide is actuated to move and mix with pre-deposited 2 &#956;L droplet on the target electrode as shown in Figure 3. The time period between successive movement is set t...

Watch this Scientific Journal Video about A Versatile Kit Based on Digital Microfluidics Droplet Actuation for Science Education at JoVE.com

A Versatile Kit Based on Digital Microfluidics Droplet Actuation for Science Education

We describe an educational kit that allows users to execute multiple experiments and gain hands-on experience on digital microfluidics.

This paper describes an educational kit based on digital microfluidics. A protocol for luminol-based chemiluminescence experiment is reported as a ...

We present a digital microfluidics educational kit based on a commercially-sourced printed circuit board that allows the user to get hands-on experience with digital microfluidics. This is a viable, low cost solution for education provided that digital PCB design files can be shared. We propose to use digital microfluidics as an educational tool because droplets are manipulated on generic electrode array platforms.Users can leverage on an extended set of electronic components now highly accessible for do-it-yourself applications to electronically interface with the droplets. Demonstrating the procedure will be Yu Hao Guo, a graduate student from the Yang Laboratory. Begin by soldering the surface mount resistors, transistors, and light emitting diodes onto the PCB board.Connect the output of the high voltage power supply board to the PCB board with the soldered components. Then connect the battery to the voltage booster board to boost the voltage from six volts to 12 volts. Connect the humidity sensor, the ultrasonic piezo atomizer, and the atomizer driver board to the microcontroller board.Turn on the microcontroller using the provided supplementary code. Adjust the variable resistor of the high voltage board and use the digital multi-meter to measure the voltage of the EWOD electrode. Wear clean nitrile gloves and apply 10 microliters of five centistoke silicone oil on the electrode area using a micropipette.Spread the oil evenly on the electrode area using a finger. Cut a piece of food wrap with dimensions 2.5 by four centimeters and place it on top of the electrode. Apply silicone oil on the electrode area using a micropipette and spread it evenly.To perform a chemiluminescence experiment, place two to five microliters of luminol solution on the target electrode using a micropipette. Place 10 microliters of 0.1%potassium ferrocyanide on the electrode which can be moved as a droplet for electrowetting. Turn on the microcontroller so that the potassium ferrocyanide droplet merges with the luminol.For fluorescent imaging, cut a one square centimeter piece of semi-transparent tape and place it between the excitation light emitting diode and EWOD electrodes. Attach the emission glass filter on the camera of the smartphone with tape and place 10 microliters of the potassium ferrocyanide solution on the electrodes. Record the video of the droplet actuation using a smartphone.For long-term droplet actuation, place one milliliter of water onto the ultrasonic atomizer. Place a droplet of potassium ferrocyanide and turn on the microcontroller. Then immediately close the lid of the enclosure.Check the droplet actuation after an hour. A representative droplet movement is shown here. For the chemiluminescence experiment, the droplet of ferrocyanide is actuated to move and mix with the pre-deposited luminol droplet on the target electrode at 12 seconds.A schematic setup of an LED serving as the light source for excitation, a semi-transparent clear office tape as a light diffuser, and the emission filter directly attached to the smartphone camera is shown here. Fluorescent imaging of the droplet containing fluorescein isothiocyanate in the dark is seen as a result of the semi-transparent tape serving as the diffuser to evenly distribute the excitation light. For a long-term experiment, successful droplet actuation can be observed.Representative humidity data under the action of an ultrasonic atomizer is shown here. This protocol can be used to develop an educational kit based on digital microfluidics. A luminol-based chemiluminescence experiment is reported as a specific example.The kit can be assembled within a short period of time and with minimal training in electronics. The simplified experiment described here can be extended to other experiments. For example, a paper test kit can be used by moving the droplet to the paper to be absorbed.A microcontroller with interface logic circuit can also be added to provide more sophisticated digital control and programmability. This protocol can benefit non-professional enthusiasts to learn and apply electronics to further advance their knowledge of the field.

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Flexible photodetectors have been intensely studied for the use of curved image sensors, which are a crucial component in bio-inspired imaging systems, ...

A Pipette-Tip Based Method for Seeding Cells to Droplet Microfluidic Platforms

Amongst various microfluidic platform designs frequently used for cellular analysis, droplet-microfluidics provides a robust tool for isolating and ...

Fabrication of Refractive-index-matched Devices for Biomedical Microfluidics

The use of microfluidic devices has emerged as a defining tool for biomedical applications. When combined with modern microscopy techniques, these devices ...

O-cresol Concentration Online Measurement Based On Near Infrared Spectroscopy Via Partial Least Square Regression

Unlike macroscopic process variables, near-infrared spectroscopy provides process information at the molecular level and can significantly improve the ...

Implementation of a Nonlinear Microscope Based on Stimulated Raman Scattering

Stimulated Raman scattering (SRS) microscopy uses near-infrared excitation light; therefore, it shares many multi-photon microscopic imaging properties. ...

A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference

We present a high-performance source of unconditional polarization-entangled photons that have a high-emission rate, a broadband distribution, are ...

Cryogenic Liquid Jets for High Repetition Rate Discovery Science

This protocol presents a detailed procedure for the operation of continuous, micron-sized cryogenic cylindrical and planar liquid jets. When operated as ...