Name: Picoinjection of Microfluidic Drops Without Metal Electrodes (Video) | JoVE Journal
Uploaded: 2014-04-18T18:00:00.000+00:00
Duration: 9 min 20 s
Description: Learn picoinjection of microfluidic drops without metal electrodes for precise reagent delivery. This simplified method enables robust device fabrication and controlled picoliter-volume injection for biochemical applications.

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5 minutes

This work was supported by the Department of Bioengineering and Therapeutic Sciences at UCSF, the California institute for Quantitative Biosciences (QB3), and the Bridging the Gap Award from the Rogers Family Foundation.

1. Design Device Dimensions and Topologies Based on Experimental Needs Using Computer Aided Design (CAD) Software
Note: Select emulsion channel diameters smaller than those of the spherical droplets. This forces the droplets into a cylindrical or &#34;sausage&#34; shape and allows for more effective picoinjection. For our purposes, we designed 30 x 30 &#956;m channels for droplets that were 50 &#956;m in diameter.
<ol>
	<li>Model picoinjection site(s) after those described by Abate et al.3 with the exception that the channels for the metal electrodes are removed, as they are unnecessary.</li>
	<li>Add channels to serve as the Faraday Moat (Figure 1)&#160;that run between picoinjection site(s) and the upstream emulsion such that they shield the droplets from the electric field. 
	Note: This prevents unintended merging.</li>
</ol>
2. Fabricate Devices Using Soft Photolithographic Techniques
<ol>
	<li>Generate a transparency photolithography mask based on the CAD file using existing commercial services.</li>
	<li>With the photomask, cure photoresist on silicon wafers to produce a device master, as described previously4.</li>
	<li>Pour PDMS mixed with curing agent (11:1 ratio) over the device master contained in a 5 cm polystyrene Petri dish.</li>
	<li>Place the master with PDMS in a vacuum desiccator for roughly 15 min&#160;to remove any air bubbles.</li>
	<li>Cure the PDMS device by placing it in a 95&#160;&#176;C oven for 1 hr. Alternatively, the PDMS will cure at RT after 24 hr.</li>
	<li>Remove the device by cutting around the perimeter with a surgical blade and carefully peeling the device from the master.</li>
	<li>Punch inlet and outlet holes into the PDMS using a 0.5 mm biopsy punch.</li>
	<li>Bond the device to a glass microscope slide using a plasma bonder4.</li>
</ol>
3. Prepare an Air Pressure Control Pump to Pressurize a Reservoir Containing the Fluid
<ol>
	<li>Modify the pump output such that the pressurized air exits through a length of 2.7 mm inner diameter polyethylene tubing.</li>
	<li>Construct it such that the tubing terminates at a luer-lock syringe tip by fitting the lumen over the nipple on the rear of the luer-lock.</li>
	<li>Seal by filling the space between the luer-lock threads and the tubing with epoxy.</li>
	<li>Attach a 27.5 G needle.</li>
</ol>
4. Prepare a Monodisperse Emulsion of Aqueous (Water-in-oil) Droplets Suspended in an Inert Fluorinated Carrier Oil with 2% (wt/wt) Dissolved Biocompatible Surfactant7
The specific reagents contained in these droplets depend on the application
<ol>
	<li>In preparation for reinjection, load the emulsion into a 1 ml syringe with a 27.5 G needle.</li>
	<li>Secure the syringe in a syringe pump and orient the pump vertically (needle upward). 
	Note: This orientation causes the droplets to pack in a layer above the carrier oil. When the pump is started, the droplets will be pushed out of the syringe at high volume fraction by the oil layer under them.</li>
</ol>
5. Prepare Reagents for Introduction to the Microfluidic Chip
<ol>
	<li>Punch three 0.5 mm holes into the cap of a 15 ml centrifuge tube (any container with a screw cap will suffice) using a biopsy punch, needle, or drill.</li>
	<li>Insert a 0.5 mm diameter wire electrode and a ~20 cm length of PE-2 tubing through two of the holes so that they reach the bottom of the tube.</li>
	<li>In the remaining hole, thread a ~2.5&#160;cm of a ~20 cm length of PE tubing such that it will rest above the fluid level.</li>
	<li>Seal any gaps on the top of the cap with UV-cured epoxy.</li>
	<li>Fill the tube with the picoinjection fluid and screw on the cap.</li>
	<li>Connect the output from the air-pressure control pump to the shorter length of tubing by inserting the needle into the lumen. The needle should fit snugly.</li>
	<li>Fill a 1 ml syringe with 1 M NaCl to serve as the Faraday Moat.</li>
	<li>Connect a 27.5 G needle and secure the syringe in a syringe pump.</li>
	<li>Fill another 1 ml syringe with carrier/spacer oil, connect a 27.5 G needle, and secure it in a syringe pump.</li>
</ol>
6. Prepare the Microfluidic Device for Picoinjection
<ol>
	<li>Connect the output tubing (longer length) from the injection fluid container to the inlet port of the picoinjection fluid on the microfluidic chip.</li>
	<li>Connect the syringe containing the 1 M NaCl to the inlet port for the Faraday Moat on the microfluidic chip with a length of PE tubing.</li>
	<li>Connect the syringe containing the carrier oil to the inlet port of the microfluidic chip with a length of PE tubing.</li>
	<li>Insert PE tubing into the emulsion outlet port on the microfluidic chip. The tubing should terminate in an emulsion collection vessel, normally a 1.5 ml centrifuge tube.</li>
	<li>Insert PE tubing into the outlet port for the Faraday Moat on the microfluidic chip. The tubing should terminate in a non-conducting and electrically isolated container to prevent a short circuit.</li>
	<li>Connect the output of the high-voltage (HV) amplifier via alligator clip to the metal electrode submerged in the picoinjection fluid.</li>
	<li>Connect the ground electrode of the HV amplifier via alligator clip to the metal of the syringe needle containing the 1 M NaCl.</li>
</ol>
7. Infuse Reagents into Microfluidic Chip
<ol>
	<li>Introduce the 1 M NaCl (Faraday Moat) to the device at a rate of 100 &#956;l/hr.</li>
	<li>Introduce the droplet emulsion and carrier oil at rates suitable for the device dimensions. For our demo device, we introduce the drops and oil at 200 and 400 &#956;l/hr, respectively. The flow rates should allow the droplets to pass the picoinjector at regular intervals separated by a gap of carrier oil.</li>
	<li>Adjust the pressure applied to the picoinjection fluid such that the fluid pressure at the picoinjection orifice is in mechanical equilibrium with the droplet channel. 
	Note: At this pressure (the Laplace pressure), the injection fluid should bulge into the droplet channel without budding off and forming its own drops (Figure 2). At these flow rates described above, we apply a pressure of ~13 psi to the injection fluid to achieve equilibrium at the injection site.</li>
</ol>
8. Begin Picoinjection
<ol>
	<li>As droplets pass the injection orifice, apply a 0-10 V, 10 kHz, AC signal amplified 1,000x by the HV-amplifier (Figure 3).</li>
	<li>Modulate the injection volume by changing the amplitude of the applied voltage. 
	Note: Higher voltages should allow for more fluid to be introduced to the droplets. In our testing, we observe stable and consistent injection at voltages between 100 and 3,000 V using injection solutions of NaCl ranging from 10-500 mM (Figure 4).</li>
</ol>

<ol><li>Kritikou, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((It%27s+cheaper+in+the+Picolab%5BTitle%5D)+AND+%22Nat.+Rev.+Genet%22%5BJournal%5D)">It's cheaper in the Picolab.</a> Nat. Rev. Genet. 6 (9), (2005).</li>
<li>Ahn, K., Agresti, J., Chong, H., Marquez, M., Weitz, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Electrocoalescence+of+drops+synchronized+by+size-dependent+flow+in+microfluidic+channels%5BTitle%5D)+AND+%22Appl.+Phys.+Lett%22%5BJournal%5D)">Electrocoalescence of drops synchronized by size-dependent flow in microfluidic channels.</a> Appl. Phys. Lett. 88 (26), (2006).</li>
<li>Abate, A. R., Hung, T., Mary, P., Agresti, J. J., Weitz, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((High-throughput+injection+with+microfluidics+using+picoinjectors%5BTitle%5D)+AND+%22Proc.+Natl.+Acad.+Sci.+U+S+A%22%5BJournal%5D)">High-throughput injection with microfluidics using picoinjectors.</a> Proc. Natl. Acad. Sci. U S A. 107, 19163-19166 (2010).</li>
<li>Harris, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Fabrication+of+a+microfluidic+device+for+the+compartmentalization+of+neuron+soma+and+axons%5BTitle%5D)+AND+%22J.+Vis.+Exp%22%5BJournal%5D)">Fabrication of a microfluidic device for the compartmentalization of neuron soma and axons.</a> J. Vis. Exp. (7), (2007).</li>
<li>Duffy, D. C., McDonald, J. C., Schueller, O. J., Whitesides, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Rapid+prototyping+of+microfluidic+systems+in+poly%28dimethylsiloxane%29%5BTitle%5D)+AND+%22Anal.+Chem%22%5BJournal%5D)">Rapid prototyping of microfluidic systems in poly(dimethylsiloxane).</a> Anal. Chem. 70 (23), 4974-4984 (1998).</li>
<li>O'Donovan, B., Eastburn, D. J., Abate, A. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Electrode-free+picoinjection+of+microfluidic+drops%5BTitle%5D)+AND+%22Lab+on+a+Chip%22%5BJournal%5D)">Electrode-free picoinjection of microfluidic drops.</a> Lab on a Chip. 12 (20), 4029-4032 (2012).</li>
<li>Holtze, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Biocompatible+surfactants+for+water-in-fluorocarbon+emulsions%5BTitle%5D)+AND+%22Lab+on+a+Chip%22%5BJournal%5D)">Biocompatible surfactants for water-in-fluorocarbon emulsions.</a> Lab on a Chip. 8 (10), 1632-1639 (2008).</li>
<li>Chung, C., Lee, M., Char, K., Ahn, K., Lee, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Droplet+dynamics+passing+through+obstructions+in+confined+microchannel+flow%5BTitle%5D)+AND+%22Microfluid.+Nanofluid%22%5BJournal%5D)">Droplet dynamics passing through obstructions in confined microchannel flow.</a> Microfluid. Nanofluid. 9, 1151-1163 (2010).</li>
<li>Herminghaus, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Dynamical+instability+of+thin+liquid+films+between+conducting+media%5BTitle%5D)+AND+%22Phys.+Rev.+Lett%22%5BJournal%5D)">Dynamical instability of thin liquid films between conducting media.</a> Phys. Rev. Lett. 83 (12), 2359-2361 (1999).</li>
<li>Priest, C., Herminghaus, S., Seemann, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Controlled+electrocoalescence+in+microfluidics%3A+Targeting+a+single+lamella%5BTitle%5D)+AND+%22Appl.+Phys.+Lett%22%5BJournal%5D)">Controlled electrocoalescence in microfluidics: Targeting a single lamella.</a> Appl. Phys. Lett. 89 (13), 134101-134103 (2006).</li>
<li>Florent, M., Siva, A. V., Hao, G., Dirk, E., Frieder, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Electrowetting-controlled+droplet+generation+in+a+microfluidic+flow-focusing+device%5BTitle%5D)+AND+%22J.+Phys%3A+Condens.+Matter%22%5BJournal%5D)">Electrowetting-controlled droplet generation in a microfluidic flow-focusing device.</a> J. Phys: Condens. Matter. 19 (46), (2007).</li>
<li>Eastburn, D. J., Sciambi, A., Abate, A. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Picoinjection+enables+digital+detection+of+RNA+with+droplet+rt-PCR%5BTitle%5D)+AND+%22PLoS+ONE%22%5BJournal%5D)">Picoinjection enables digital detection of RNA with droplet rt-PCR.</a> PLoS ONE. 8 (4), (2013).</li>
</ol>

We do not fully understand exact physical mechanism behind the relationship between the applied voltage and injection volume observed in our experiments. The lab&#39;s interests and relevant areas of expertise are not well-suited for pursuing this lingering question. We encourage those with more physics and engineering acumen to explore this phenomenon.

The relationship between injection volume and applied voltage is dependent on many factors including device dimensions, length of the tubing carrying the picoinjection fluid to the device, molarity of picoinjection fluid, and the velocity of the droplets as they pass they injector. For this reason we recommend that the volume/voltage relationship be characterized before each run of picoinjection by measuring injection volumes at the edges of the working ranges of voltage and molarity. Additionally, at higher voltages and...

In droplet-based microfluidics, micron-scale aqueous droplets are used as &#34;test tubes&#34; for biological reactions. The advantage to performing reactions in the tiny droplets is that each drop uses only a few pl of reagent and, with microfluidics, the drops can be formed and processed at kilohertz rates1.&#160;Combined, these properties allow millions of reactions with individual cells, nucleic acid molecules, or compounds to be performed in a matter of min&#160;with &#956;l&#160;of total material.
To use drops for applications like these, techniques are needed for adding controlled volumes of reagents to the drops; such operations are analogous to pipetting into test tubes. One method for accomplishing this is electrocoalescence, wherein a drop of reagent is merged with the target drop by applying an electric field. The electric field disrupts the arrangement of surfactant molecules on the interfaces of the drops, inducing a thin-film instability and triggering coalescence in emulsions that are otherwise stable2. Electrically-induced merging is also exploited in the design of the picoinjector, a device that injects reagents into drops as they flow past a pressurized channel3. To apply the electric field, picoinjector devices utilize metal electrodes, but the integration of metal electrodes into microfluidic chips is often a complex and error-prone process as the liquid-solder wires are easily compromised by air bubbles or dust and other debris in the channel, as well as fractures from stress or bending during device setup.
Here we present a method to perform picoinjection without the use of metal electrodes, making the fabrication simpler and more robust. To trigger picoinjection, we instead use the injection fluid itself as an electrode, since most biological reagents contain dissolved electrolytes and are conductive. We also add a &#34;Faraday Moat&#34; to shield sensitive regions of the device and act as a universal ground (Figure 1). The moat electrically isolates the droplets upstream of the picoinjection site by providing a ground, preventing unintended droplet merger. An added benefit of our technique is that the volume injected into the drops depends on the magnitude of the applied voltage, allowing it to be adjusted by tuning the applied signal.
We fabricate our devices in poly(dimethylsiloxane) (PDMS) using soft photolithographic techniques4,5. Our approach is compatible with devices fabricated in other materials, like resins, plastics, and epoxies. The channels have heights and widths of 30&#160;&#956;m, which are optimal for working with droplets 50 &#956;m in diameter (65 pl). We introduce reagents via polyethelene tubing (0.3/1.09 mm inner/outer diameter) inserted into ports created during device fabrication with 0.50 mm biopsy punches, similar to methods described previously5. The exact makeup of the injection fluid depends on the specific application. The fluid need only contain dissolved electrolytes at concentrations high enough to yield sufficient conductivity for the electrical signal to be transmitted to the picoinjector. In bench testing, we have found that ionic concentrations greater than 10 mM should suffice6, though this value and fluid conductivities depend on the specific device dimensions and magnitude of the applied voltage.

<table><tbody><tr><td>1 ml Luer-Lok&amp;trade; syringes</td><td>BD Medical</td><td>309628</td><td></td></tr><tr><td>LocTite UV-cured adhesive</td><td>Henkel</td><td>35241</td><td></td></tr><tr><td>PE-2 tubing</td><td>Scientific Commodities</td><td>BB31695-PE/2</td><td></td></tr><tr><td>Novec HFE-7500</td><td>3M</td><td>98-0212-2928-5</td><td></td></tr><tr><td>NaCl</td><td>Sigma Aldrich</td><td>S9888</td><td></td></tr><tr><td>1.5 ml centrifuge tubes</td><td>Eppendorf</td><td>22363531</td><td></td></tr><tr><td>BD Falcon 15 ml tube</td><td>BD Biosciences</td><td>352097</td><td></td></tr><tr><td>Air pressure control pump</td><td>Control Air Inc.</td><td></td><td>We recommend one under the control of DAQ and control software</td></tr><tr><td>Syringe pumps</td><td>New Era</td><td></td><td>Must be capable of holding 1 ml syringes and flowing at rates as low as 100 &amp;#956;l/hr</td></tr><tr><td>HV-amplfier</td><td></td><td></td><td>Must be capable of 1,000x amplification of signals between 0.01 and 10 V</td></tr><tr><td>Plasma bonder/cleaner</td><td>Harrick Plasma</td><td></td><td></td></tr><tr><td>3&amp;rdquo; silicon wafers</td><td>Sigma Aldrich</td><td>647535</td><td></td></tr><tr><td>PDMS</td><td>Dow Corning</td><td></td><td>Sylgard 184 with curing agent should be included</td></tr><tr><td>SU-8 photoresist</td><td>MicroChem</td><td></td><td>Viscocity depends on device dimensions</td></tr></tbody></table>

picoinjection of microfluidic drops without metal electrodes

Picoinjection of Microfluidic Drops Without Metal Electrodes

Existing methods for picoinjecting reagents into microfluidic drops require metal electrodes integrated into the microfluidic chip. The integration of these electrodes adds cumbersome and error-prone steps to the device fabrication process. We have developed a technique that obviates the needs for metal electrodes during picoinjection. Instead, it uses the injection fluid itself as an electrode, since most biological reagents contain dissolved electrolytes and are conductive. By eliminating the electrodes, we reduce device fabrication time and complexity, and make the devices more robust. In addition, with our approach, the injection volume depends on the voltage applied to the picoinjection solution; this allows us to rapidly adjust the volume injected by modulating the applied voltage. We demonstrate that our technique is compatible with reagents incorporating common biological compounds, including buffers, enzymes, and nucleic acids.

Microscopic images taken at the picoinjection site show that electrification of the picoinjection fluid is enough to trigger injection (Figure 2). The injected volume can be controlled by modulating the amplitude of the applied voltage, with higher voltages allowing for higher injection volumes. We plot the injection volume versus the magnitude of the applied voltage for three representative molarities of injection fluid in (Figure 3). To demonstrate the speed our method, we selectively ...

We have developed a technique for picoinjecting microfluidic drops that does not require metal electrodes. As such, devices incorporating our technique are simpler to fabricate and to use.

Existing methods for picoinjecting reagents into microfluidic drops require metal electrodes integrated into the microfluidic chip. The integration of ...

The overall goal of this procedure is to design, fabricate, and utilize microfluidic chips capable of precisely and controllably injecting reagents into water in oil droplets, a process known as pico injection. This is achieved by first designing a device with an emulsion channel that narrows to a diameter smaller than that of the spherical droplets and spaces them evenly within inert carrier oil. As a second step, the water and oil droplets are introduced into the device and flow to the injection site.A perpendicular channel containing the reagents to be injected. Next, a high voltage is applied to the injection fluid as droplets pass the injection site in order to cause the droplets and injection fluid to merge Results are obtained that show by tuning the magnitude of the applied voltage, the volume of injected reagent can be precisely controlled at picoliter resolutions. This technique was born outta the need to simplify the fabrication of our devices by eliminating the need for metal electrodes.The advantages over existing techniques, so the ease and simplicity of device design, fabrication, and use The metal electrodes used in previous methods for prone to brake and sensitive to dust and debris in the channels during fabrication. By eliminating the electrodes, we've made our devices more robust and improved our fabrication efficiency. The first step is to design a microfluidic chip based on the needs of the experiment.Use computer aided design software for this in order to make use of photo lithographic techniques later. This chip design has emulsion channels that are smaller than the spherical droplets to be used to allow for more effective pico injection. The pico injection site is based on a design found in the literature with the metal electrodes removed.Additional channels serve as a Faraday moat to shield upstream droplets from the electric field. Once the design is completed, use soft photo lithographic techniques to fabricate the devices, then bond them to a glass microscope slide with the device ready for use. Prepare an air pressure control pump to pressurize a fluid containing reservoir.Do this by modifying the pump output so that the pressurized air exits through a length of polyethylene tubing with an inner diameter of 2.7 millimeters. Terminate the tubing by fitting it over the nipple at the rear of a syringe tip. After sealing the space between the syringe and the tubing with epoxy, attach a 27.5 gauge needle using reagents appropriate to the experiment.Prepare a uniform emulsion of aqueous droplets suspended in carrier oil. Load the emulsion into a one milliliter syringe equipped with a 27.5 gauge needle. Then secure the syringe in a syringe pump and orient it with a needle upward.The next step is to prepare reagents for introduction into the microfluidic device and their reservoirs. Begin with a 15 milliliter centrifuge tube and cap. Use a biopsy punch or other convenient tool to punch three 0.5 millimeter holes into the cap.Prepare a wire electrode with a diameter of 0.5 millimeters and a length of a few centimeters longer than the centrifuge tube. Insert this electrode into one hole in the cap. Make sure it reaches the bottom of the tube and extends a few centimeters beyond the top.Next, prepare an approximately 20 centimeter length of polyethylene tubing. Insert this in a second hole. Again, it should reach the bottom of the tube in the remaining hole.Thread about 2.5 centimeters of polyethylene tubing. This tube will rest above the fluid level. Apply UV curing epoxy to seal gaps on the top of the cap.When the curing is complete, fill the tube with the desired pico injection fluid here, 100 millimolar sodium chloride and screw on the cap. Connect the output from the air pressure control pump to the shorter length of tubing in the cap. By inserting the needle into the lumen, the needle should fit snugly.Place the centrifuge tube in its holder. Proceed by filling a one milliliter syringe with one molar sodium chloride. To serve as the Faraday moat fluid connect a 27.5 gauge needle and secure the syringe on a syringe pump.Fill another one milliliter syringe with carrier spacer oil. Connect a 27.5 gauge needle and secure it in a syringe pump. At this point, connections can be made to the microfluidic chip.First, ensure the chip is secured on a flat surface. Next, bring the open end of the long tube from the injection fluid container to the chip. Connect this tube to the inlet port of the pico injection fluid on the microfluidic chip.Then attach polyethylene tubing to the syringe containing sodium chloride and extend it to the chip. Attach it to the inlet port for the Faraday moat. Also, use tubing to connect the syringe containing the carrier oil to its inlet port on the device.Terminate a tube coming from the emulsion outlet port into a collection vessel. Finally, use tubing to connect the outlet port of the Faraday moat to a non conducting electrically isolated container. In the end, the microfluidic chip appears like this.Now take a wire from the ground of a high voltage amplifier and extend it to the needle of the syringe with sodium chloride. Use an alligator clip to attach the wire to the needle. Extend another wire from the high voltage output of the amplifier to the electrode immersed in the pico injection fluid.Use an alligator clip to make the connection as input to the amplifier. Use the computer output of a software controlled waveform generator. Begin infusion of the system by introducing the one molar sodium chloride faraday mote fluid to the device at 100 microliters per hour.After that, start the droplet, emulsion and carrier oil to allow droplets to pass the pico injector at regular intervals, separated by a gap of carrier oil. Adjust the pressure applied to the pico injection fluid, such that the fluid at the pico injection orifice bulges into the droplet channel, but does not but off to form its own drops. Employ the waveform generator to produce a 10 kilohertz a C signal with an amplitude of zero to 10 volts to be amplified a thousand times by the high voltage amplifier.To achieve pico injection. Apply this signal to the droplets as they pass the injection orifice and use the amplitude as a parameter. This movie shows the selective injection of droplets depending on the presence of a fluorescent dye.In this instance, 200 drops per second passed by the injector, but rates of up to 10, 000 per second are possible with a right droplet detection mechanism. These figures show the injected volume fraction as a function of applied voltage for different molarity injection fluids. It is believed that higher voltages cause an earlier onset of coalescence leading to increased injection durations and volumes.This two dimensional heat map shows the relationship between ionic solution molarity, and the voltage required to achieve injection volumes. Lower molarity solutions require higher voltages since they more readily reduce the electric field at the injection site. After watching this video, you should have a good understanding of how to quickly and robustly design and fabricate micro fluidic devices that allow for precise and controllable injection of reagents into your droplets.Don't forget that working with high voltage can be extremely hazardous precautions, such as proper grounding, personal protective equipment, and built-in fail safes should always be employed.

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Engineering

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Learn picoinjection of microfluidic drops without metal electrodes for precise reagent delivery. This simplified method enables robust device fabrication and controlled picoliter-volume injection for biochemical applications.

Picoinjection of Microfluidic Drops Without Metal Electrodes

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