Name: Polymeric Microneedle Array Fabrication by Photolithography (Video) | JoVE Journal
Uploaded: 2015-11-17T13:00:00.000+00:00
Duration: 8 min 15 s
Description: Learn mold-free fabrication of polymeric microneedles using photolithography for painless transdermal drug delivery. This precise UV polymerization method enables controlled microneedle dimensions without high temperatures.

ai_agent_IP

ai_agent

maintenance

instantTrialDurationMinutes

isBiopharma

enableNewMyJoveSectionDesign

educationFeatures

seoMetaApi

ai_copilot_institution_blacklist

ai_chat_institution_blacklist

freeAccessWindow

ssoRoleCapture

scheduledMaintenanceBanner

joveLabsFeatures

disable_autoplay_for_bots

extended_trial_duration

5 minutes

This study was supported by a Singapore National Research Foundation (NRF) Grant NRF2012NRF-POC001-043.

1. Photomask Fabrication
<ol>
	<li>Clean a 4&#8221; glass wafer with piranha solution (H2SO4/H2O2 in 2:1 ratio) for 20 min at 120 &#176;C by immersion in a quartz tank.</li>
	<li>Deposit a layer of Chromium/Gold (30 nm of Cr/1 &#181;m of Au) layer on the glass wafer using an e-beam evaporator7 (Figure 1A).
	<ol>
		<li>Place the wafers in an e-beam evaporator. Once the vacuum reaches 5 x 10-6 Torr, turn on the high voltage source (10 kV). Control the thickness by the monitor control panel.</li>
		<li>Pre-clean each material for 30 sec using the e-beam gun, keeping the shutter &#8220;OFF&#8221; (in order to avoid the deposition on the wafers).</li>
	</ol>
	</li>
	<li>Generate a Cr/Au photoresist masking layer for deep wet etching of the glass.
	<ol>
		<li>Apply a 2 &#181;m thick photoresist by spinning 5 ml of the solution for 30 sec at 3,000 rpm using a spin-spray coater system. Prebake the photoresist on a hotplate at 100 &#176;C for 1.5 min.</li>
		<li>Expose and hard bake the photoresist at 120 &#176;C for 30 min on a hot plate. It is critical to generate a hydrophobic surface and a strong adhesion of the photoresist to the metal layer. Pattern the Cr/Au layer using Cr and Au etchants through the photoresist mask8,9.</li>
	</ol>
	</li>
	<li>For protection of the un-patterned glass surface, temporarily bond the glass wafer to a dummy silicon wafer.9
	<ol>
		<li>Place the glass wafer on a hot plate at 110 &#176;C and melt the wax on the opposite side of the glass wafer (in such a way that the entire surface of the wafer is covered with wax).</li>
		<li>Place a dummy silicon wafer in contact with the glass wafer and press to remove the excess wax. In order to avoid spilling of the wax, place a clean room tissue paper on the hotplate.</li>
	</ol>
	</li>
	<li>Perform isotropic etching of the lens using optimized hydrofluoric acid (49% v/v) and hydrochloric acid (37% v/v) solution ( in a volumetric ratio of 10:1) with a magnetic stirrer for 8.5 min.10 Presence of the HCl is critical in achieving a good surface quality of generated lenses.
	<ol>
		<li>Ensure that the etching rate is 7 &#181;m/min; using a total volume of 200 ml of etching solution. Perform etching in a plastic container and take safety precaution for this processing step.</li>
		<li>Clean the wafer in the deionized (DI) water by rinsing and further drying at RT.</li>
	</ol>
	</li>
	<li>After the process completion, separate the glass wafer from the dummy silicon wafer and warm up the wax using a hot plate at 100 &#176;C for 15 sec. As the wax melts at this temperature, detach the glass wafer from the dummy silicon wafer.</li>
	<li>Remove remaining wax, the photoresist and the overhanging Cr/Au layers at the edges of the lenses using ultrasonication for 1 hr using N-methyl-2-pyrrolidone as the solvent at 80 &#176;C in an ultrasonic tank.</li>
	<li>Create a PDMS mold replica of the microlenses fabricated on the photomasks11.</li>
	<li>Characterize the photomask dimensions (length and width) and the microlenses PDMS mold (depth and diameter) replicas using a scanning electron microscope and stereomicroscope respectively.12-14</li>
</ol>
2. MN Shafts Fabrication
<ol>
	<li>Create a cavity of 2.5 cm &#215; 0.9 cm using the glass slides mounted on either sides of a glass. The number of the glass slides stacked on either side will determine the height of the cavity known as spacer thickness (Figure 1B).</li>
	<li>Secure each layer of the glass slide by applying a thin layer of the prepolymer solution containing Poly(ethylene glycol) diacrylate (PEGDA, MW = 258 Da) with 0.5% w/w 2-hydroxy-2-methyl-propiophenone (HMP) onto the glass slide followed by irradiation of the set up with the high intensity ultraviolet (UV) light for 2 sec.</li>
	<li>Position the photomask (previously fabricated) with the Cr/Au coated surfaces facing the interior of the cavity. Ensure that the sides of the cavity walls are not obscuring the lenses embedded in the photomask.</li>
	<li>Fill the cavity with the prepolymer solution until the Cr/Au coated surface is in contact with the solution without any visible bubbles.</li>
	<li>Irradiate the setup with high intensity UV light of a desired intensity for 1 sec at a distance of 3.5 cm from the UV source using the UV curing station with a UV filter range of 320-500 nm. Use a collimating adaptor with the UV light probe.</li>
	<li>Measure the intensity of UV light used using a radiometer.</li>
	<li>Following UV exposure, remove the photomask with the array of MNs. Pour the excess prepolymer solution that is not polymerized in the process back into its original container for reuse.</li>
	<li>Quantify the length and tip diameter of the MNs using a stereomicroscope according to manufacturer&#8217;s instructions.</li>
</ol>
3. MN Backing Layer Fabrication
<ol>
	<li>With forceps, place the MNs (previously fabricated) attached onto the photomask in a well of a 24-well plate as shown in the Figure 1C.</li>
	<li>Add a specified volume (300 - 400 &#181;l) of the prepolymer solution into the well until the needles are submerged to a desired height. This volume determines the thickness of the resultant backing layer.</li>
	<li>Irradiate the setup with high intensity UV light (15.1 W/cm2), 10.5 cm away from the UV source for a duration of 1 sec.</li>
	<li>Separate the backing layer on the MN array from the photomask using a sharp blade.</li>
	<li>Quantify the length, tip diameter and base diameter of the MNs with the backing layer using a stereomicroscope according to manufacturer&#8217;s instructions.</li>
</ol>

<ol><li>Zhou, C. P., Liu, Y. L., Wang, H. L., Zhang, P. X., Zhang, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Transdermal+delivery+of+insulin+using+microneedle+rollers+in+vivo%5BTitle%5D)+AND+%22International+journal+of+pharmaceutics%22%5BJournal%5D)">Transdermal delivery of insulin using microneedle rollers in vivo.</a> International journal of pharmaceutics. 392, 127-133 (2010).</li>
<li>Lee, J. W., Choi, S. O., Felner, E. I., Prausnitz, M. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Dissolving+microneedle+patch+for+transdermal+delivery+of+human+growth+hormone%5BTitle%5D)+AND+%22Small%22%5BJournal%5D)">Dissolving microneedle patch for transdermal delivery of human growth hormone.</a> Small. 7, 531-539 (2011).</li>
<li>Raphael, A. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((needle-free+vaccinations+in+skin+using+multi+layered%2C+densely-packed+dissolving+microprojection+arrays%5BTitle%5D)+AND+%22Small%22%5BJournal%5D)">needle-free vaccinations in skin using multi layered, densely-packed dissolving microprojection arrays.</a> Small. 6, 1785-1793 (2010).</li>
<li>Lee, J. W., Han, M. R., Park, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Polymer+microneedles+for+transdermal+drug+delivery%5BTitle%5D)+AND+%22Journal+of+drug+targeting%22%5BJournal%5D)">Polymer microneedles for transdermal drug delivery.</a> Journal of drug targeting. 21, 211-223 (2012).</li>
<li>Kochhar, J. S., Goh, W. J., Chan, S. Y., Kang, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+simple+method+of+microneedle+array+fabrication+for+transdermal+drug+delivery%5BTitle%5D)+AND+%22Drug+development+and+industrial+pharmacy%22%5BJournal%5D)">A simple method of microneedle array fabrication for transdermal drug delivery.</a> Drug development and industrial pharmacy. 39, 299-309 (2013).</li>
<li>Kochhar, J. S., Zou, S., Chan, S. Y., Kang, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Protein+encapsulation+in+polymeric+microneedles+by+photolithography%5BTitle%5D)+AND+%22International+journal+of+nanomedicine%22%5BJournal%5D)">Protein encapsulation in polymeric microneedles by photolithography.</a> International journal of nanomedicine. 7, 3143-3154 (2012).</li>
<li>Tay, F. E. H., Iliescu, C., Jing, J., Miao, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Defect-free+wet+etching+through+pyrex+glass+using+Cr%2FAu+mask%5BTitle%5D)+AND+%22Microsystem+Technologies%22%5BJournal%5D)">Defect-free wet etching through pyrex glass using Cr/Au mask.</a> Microsystem Technologies. 12, 935-939 (2006).</li>
<li>Iliescu, C., Chen, B., Miao, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((On+the+wet+etching+of+Pyrex+glass%5BTitle%5D)+AND+%22Sensors+and+Actuators%2C+A%3A+Physical%22%5BJournal%5D)">On the wet etching of Pyrex glass.</a> Sensors and Actuators, A: Physical. 143, 154-161 (2008).</li>
<li>Iliescu, C., Taylor, H., Avram, M., Miao, J., Franssila, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+practical+guide+for+the+fabrication+of+microfluidic+devices+using+glass+and+silicon%5BTitle%5D)+AND+%22Biomicrofluidics%22%5BJournal%5D)">A practical guide for the fabrication of microfluidic devices using glass and silicon.</a> Biomicrofluidics. 6, 16505-16516 (2012).</li>
<li>Iliescu, C., Jing, J., Tay, F. E. H., Miao, J., Sun, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Characterization+of+masking+layers+for+deep+wet+etching+of+glass+in+an+improved+HF%2FHCl+solution%5BTitle%5D)+AND+%22Surface+and+Coatings+Technology%22%5BJournal%5D)">Characterization of masking layers for deep wet etching of glass in an improved HF/HCl solution.</a> Surface and Coatings Technology. 198, 314-318 (2005).</li>
<li>Pan, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Fabrication+of+a+3D+hair+follicle-like+hydrogel+by+soft+lithography%5BTitle%5D)+AND+%22Journal+of+biomedical+materials+research.+Part+A%22%5BJournal%5D)">Fabrication of a 3D hair follicle-like hydrogel by soft lithography.</a> Journal of biomedical materials research. Part A. 101, 3159-3169 (2013).</li>
<li>Jay, T. R., Stern, M. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Preshaping+photoresist+for+refractive+microlens+fabrication%5BTitle%5D)+AND+%22P+Soc+Photo-Opt+Ins%22%5BJournal%5D)">Preshaping photoresist for refractive microlens fabrication.</a> P Soc Photo-Opt Ins. 1992, 275-282 (1993).</li>
<li>Friedman, G. B., Sandhu, H. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Longitudinal+Spherical+Aberration+of+a+Thin+Lens%5BTitle%5D)+AND+%22Am+J+Phys%22%5BJournal%5D)">Longitudinal Spherical Aberration of a Thin Lens.</a> Am J Phys. 35, 628(1967).</li>
<li>Xu, Q. A., Li, J., Zhang, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Collimated+the+laser+diode+beam+by+the+focus+lens%5BTitle%5D)+AND+%22Semiconductor+Lasers+and+Applications+IV%22%5BJournal%5D)">Collimated the laser diode beam by the focus lens.</a> Semiconductor Lasers and Applications IV. 7844, (2010).</li>
<li>Lin, T. W., Chen, C. F., Yang, J. J., Liao, Y. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+dual-directional+light-control+film+with+a+high-sag+and+high-asymmetrical-shape+microlens+array+fabricated+by+a+UV+imprinting+process%5BTitle%5D)+AND+%22J+Micromech+Microeng%22%5BJournal%5D)">A dual-directional light-control film with a high-sag and high-asymmetrical-shape microlens array fabricated by a UV imprinting process.</a> J Micromech Microeng. 18, (2008).</li>
<li>Dunne, S. M., Millar, B. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Effect+of+distance+from+curing+light+tip+to+restoration+surface+on+depth+of+cure+of+composite+resin%5BTitle%5D)+AND+%22Prim+Dent+Care%22%5BJournal%5D)">Effect of distance from curing light tip to restoration surface on depth of cure of composite resin.</a> Prim Dent Care. 15, 147-152 (2008).</li>
<li>Kochhar, J. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Microneedle+integrated+transdermal+patch+for+fast+onset+and+sustained+delivery+of+lidocaine%5BTitle%5D)+AND+%22Molecular+pharmaceutics%22%5BJournal%5D)">Microneedle integrated transdermal patch for fast onset and sustained delivery of lidocaine.</a> Molecular pharmaceutics. 10, 4272-4280 (2013).</li>
<li>Kochhar, J. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Direct+microneedle+array+fabrication+off+a+photomask+to+deliver+collagen+through+skin%5BTitle%5D)+AND+%22Pharmaceutical+research%22%5BJournal%5D)">Direct microneedle array fabrication off a photomask to deliver collagen through skin.</a> Pharmaceutical research. 31, 1724-1734 (2014).</li>
</ol>

The authors declare no conflict of Interest.

The protocol described above for fabrication of the MNs array has been presented to fabricate the MNs array of ~1 cm2. The arrays can be scaled up by creating a large size cavity and by using a larger photomask. The increased cavity size can be created by increasing the width between the spacers on either side. Though each step to fabricate the MN arrays in the protocol was important, the most crucial steps were: the photomask positioning, the filling of prepolymer solution, and irradiation of the setup. Posit...

Transdermal drug delivery offers an attractive alternative approach for drug administration, especially for biomolecules, which are almost exclusively administered by hypodermic injections. However, skin, especially the top layer (the stratum corneum), is a formidable barrier preventing exogenous molecules from entering the human body. Recently, MN devices have emerged as enabling tools to deliver drugs through skin. The MN devices create temporary pores inside the stratum corneum to allow the passage of drug molecules to achieve the desired physiological activity with improved patient compliance and convenience1-3.
Various fabrication methods have been adopted to fabricate polymeric MNs4. However, they usually involve complicated and multiple step processes requiring long times and/or high temperatures to fabricate MNs arrays.4 To simplify the fabrication process, a single step mold-free process using a photomask was developed recently5,6. However, with this method, fabricated MNs had blunt needle tips, as no mechanism was in place to modify the ultraviolet (UV) light path involved in photolithography.
In this study, embedded microlenses in the photomask have been proposed to define the geometry of the MNs. The protocol to fabricate photomasks consisting of embedded microlenses and subsequently MN fabrication with sharp tips using the photomask are reported.

<table><tbody><tr><td>Poly(ethylene glycol) diacrylate (PEGDA Mn=258)</td><td>SIGMA&amp;nbsp;</td><td>475629-500ML</td><td></td></tr><tr><td>2-hydroxy-2-methyl-propiophenone (HMP)</td><td>SIGMA&amp;nbsp;</td><td>405655-50ML</td><td></td></tr><tr><td>Bovine collagen type 1, FITC conjugate&amp;nbsp;</td><td>SIGMA&amp;nbsp;</td><td>C4361</td><td></td></tr><tr><td>UV curing station&amp;nbsp;&amp;nbsp;&amp;nbsp;</td><td>EXFO Photonic Solutions Inc., Canada</td><td>OmniCure S2000-XL</td><td></td></tr><tr><td>Collimating Adaptor&amp;nbsp;</td><td>EXFO Photonic Solutions Inc., Canada</td><td>EXFO 810-00042</td><td></td></tr><tr><td>24-well plate</td><td>Thermo Fisher Scientific, USA</td><td></td><td></td></tr><tr><td>Nikon SMZ 1500 stereomicroscope&amp;nbsp;</td><td>Nikon, Japan</td><td></td><td></td></tr><tr><td>Dillon GL-500 digital force gauge&amp;nbsp;</td><td>Dillon, USA</td><td></td><td></td></tr><tr><td>A-1R confocal microscope&amp;nbsp;</td><td>Nikon, Japan</td><td></td><td></td></tr></tbody></table>

polymeric microneedle array fabrication by photolithography

Polymeric Microneedle Array Fabrication by Photolithography

This manuscript describes the fabrication of polymeric microneedle (MN) arrays by photolithography. It involves a simple mold-free process by using a photomask consisting of embedded micro-lenses. Embedded micro-lenses were found to influence MN geometry (sharpness). Robust MN arrays with tip diameters ranging between 41.5 &#181;m &#177; 8.4 &#181;m and 71.6 &#181;m &#177; 13.7 &#181;m, with two different lengths (1,336 &#181;m &#177; 193 &#181;m and 957 &#181;m &#177; 171 &#181;m) were fabricated. These MN arrays may provide potential applications in delivery of low molecular and macromolecular therapeutic agents through skin.

The geometry of the MNs can be significantly affected by the photomask characteristics and embedded microlens. The degree of refraction affects the transmission path of the UV rays, which influenced the MN geometry (Figure 2A). Each microlens was found to have a 350 µm diameter, a 130 µm flattened convex surface, and a 62.3 µm depth (Figure 2B-D). Using the Pythagoras theorem, the radius of curvature of the first surface was found to be 272.89 µm. The focal length was calculated to be 50...

Here, we present a protocol describing a mold-free fabrication process of the polymeric microneedles by photolithography.

This manuscript describes the fabrication of polymeric microneedle (MN) arrays by photolithography. It involves a simple mold-free process by using a ...

The overall goal of this procedure is to fabricate a sharp polymeric microneedle array, which may provide potential applications in the painless delivery of low molecular and macromolecular therapeutic agents through the skin. This is accomplished by first fabricating a photo mask consisting of embedded micro lenses via patterned isotropic etching. The second step is to fabricate microneedle shafts by placing the embedded photo mask over a bath of pre polymer solution and focusing UV light into the solution through the micro lenses polymerizing the exposed solution.The final step is to fabricate the backing layer to support the microneedle shafts. This is accomplished by placing the microneedles pointy site up into a plate, then adding a pre polymer solution and polymerizing the solution with UV light. Ultimately, the characteristic properties of the microneedles, including length, diameter, and the apex angle, can be observed using a stereo microscope.The main advantage of this technique over existing methods like micro molding, is that it is faster. It is mold-free process, and it does not require the use of high temperature. This method can help answer key questions in microfabrication, like use of micro lens to modify the path of UV light and the polymerization process.This technique can be used to fabricate polymeric macro needles, which are used for for transoral drug delivery, although we're only demonstrating how to fabricate blank microneedles. This technique can also be used to fabricate drug leading microneedles. Begin cleaning a four inch glass wafer by immersing it into a quartz tank filled with Piha solution for 20 minutes at 120 degrees Celsius.Then rinse the wafer in distilled water and dry it using compressed air. When finished in the e-beam evaporator, place the wafer into a spin coder setup and add five milliliters of a photo resist to the center of the wafer. Spin the wafer at 3000 RPMs for 30 seconds to produce a two micrometer thick photo resist layer.Next, pre-bake the photo resist on a hot plate at 100 degrees Celsius for one and a half minutes, and then place the master photo mask and wafer into the photo mask aligner, and expose the wafer once exposed hard. Bake the photo resist at 120 degrees Celsius for 30 minutes on a hot plate. Then etch the pattern into the glass wafer using a solution of chromium and gold etchings at room temperature for one hour, place the etched glass wafer on a hot plate at 110 degrees Celsius and melt wax on the opposite side of the glass wafer so that the entire surface of the wafer is covered with wax.Temporarily bond the glass wafer to a dummy silicon wafer by placing a silicon wafer in contact with the glass wafer and pressing firmly to remove the excess wax. Next, prepare a 200 milliliter bath of 10 parts, 49%hydrofluoric acid, and one part 37%hydrochloric acid in a plastic container with a magnetic stir. Add the sample and etch the micro lenses at a rate of seven micrometers per minute for eight and a half minutes while stirring.When finished, clean the wafer using deionized water and dry it at room temperature. Once dry, place the wafer onto a hot plate, preheated to 100 degrees Celsius for 15 seconds. Then separate the glass wafer from the dummy silicon wafer.Place the glass wafer into an ultrasonic tank containing n methyl to Perone at 80 degrees Celsius and use ultras sunation for one hour to remove the remaining wax, the photo resist, and the overhanging chromium and gold layers at the edges of the lenses. Stack glass slides on either side of a rectangular shaped cavity to set the maximum height of the microneedles. Secure each layer of the glass slide by applying a thin layer of pre polymer solution onto the glass slides in between each layer.When finished, irradiate the setup with a high intensity ultraviolet light for two seconds to fix the slides into place. Next, position the photo mask so that the chromium gold coated surface is facing the interior of the cavity. Ensure that the sides of the cavity walls are not obscuring.The lenses embedded in the photo mask. Fill the cavity with the pre polymer solution until the chromium gold coated surface comes into contact with the solution without any visible bubbles. Then place the setup into a UV curing station and place a radiometer next to the setup to measure the intensity of the UV light.Irradiate the setup with high intensity UV light between 320 and 500 nanometers for one second at a distance of 3.5 centimeters from the UV source. Following UV exposure, remove the photo mask with the array of microneedles and pour the excess pre polymer solution back into its original container for reuse. Quantify the length and tip diameter of the microneedles using a stereo microscope using standard techniques with forceps.Place the microneedles attached to the photo mask into a well of a 24 well plate needle side up. Add 300 to 400 microliters of the pre polymer solution into the well until the needles are submerged to the height of the desired backing layer. Next, irradiate the setup with high intensity UV light measuring 15.1 watts per square centimeter from 10.5 centimeters away for a duration of one second.Once the backing layer has polymerized, separate the backing layer on the microneedle array from the photo mask using a sharp blade. Then quantify the length tip, diameter, and base diameter of the microneedles with the backing layer using a stereo microscope. The effective UV intensity on the microneedle length and tip diameter was studied by varying intensity of the UV light from 3.14 to 15.1 watts per square centimeter at a constant focal length and light source distance.It was found that the average microneedle length and tip diameter increased with increasing intensity. Shown here are the effects of 300 microliters versus 400 microliters of backing material on the overall length of the microneedles, as well as the fracture force of the needles as expected with more backing material, the needles are shorter overall, but they also gain additional fracture force due to the extra support. After watching this video, I hope you have a good understanding of how to fabricate polymeric macro needles Once mastered, this technique can be performed in five to 10 minutes.If the procedure is performed carefully and the photo mask is ready, Please remember how this materials such as hydrofluoric acid and the UV reefs are used, so personal protection gears should be worn at all times.

polymeric-microneedle-array-fabrication-by-photolithography

Research

JoVE Journal

Bioengineering

This article details the construction of a multiplexed microneedle-based sensor. The device is being developed for in situ sampling and electrochemical analysis of multiple analytes in a rapid and selective manner. We envision clinical medicine and biomedical research uses for these microneedle-based sensors.

Hollow Microneedle-based Sensor for Multiplexed Transdermal Electrochemical Sensing

The fabrication method for fine interdigitated electrodes (gap and width: 20 µm) at the tip of a hypodermic needle (diameter: 720 µm) is demonstrated using a spray coating and flexible film photomask in the photolithography process.

Fabrication of Fine Electrodes on the Tip of Hypodermic Needle Using Photoresist Spray Coating and Flexible Photomask for Biomedical Applications

This article introduces a unique method for fabricating master molds with an air-vent hole to prevent air entrapment during viscous polymer casting, enabling the fabrication of gelatin microneedles with sharp tips. By reducing the casting volume of high-viscosity gelatin, thin-walled hollow pyramidal microneedles could also be fabricated.

Fabrication of a Master Mold for Microneedles with a Micron-sized Air-vent Hole

This protocol describes the fabrication of dissolvable microneedle patches incorporating α-lactalbumin nanomicelles loaded with capsaicin. The method offers a reproducible, minimally invasive approach for targeted transdermal delivery of hydrophobic bioactives to adipose tissue, facilitating efficient local fat reduction and potentially expanding applications in obesity management.

Fabrication of Dissolvable Microneedle Patches Loaded with &#945;-Lactalbumin Nanomicelles for Transdermal Capsaicin Delivery and Adipose Tissue Reduction

The present work aims to serve as a practical guide enabling researchers to prepare their own DMAP devices using the solvent-casting method, also known as micromolding, and to perform basic characterization.

Dissolving Microneedle Array Patches Manufactured By Solvent Casting Technique and Essential Characterization of Microneedle-Based Biomedical Devices

Simple techniques are described for the rapid production of microfabricated neural culture systems using a digital micromirror device for dynamic mask projection lithography on regular cell culture substrates.  These culture systems may be more representative of natural biological architecture, and the techniques described could be adapted for numerous applications.

Fabrication of Micropatterned Hydrogels for Neural Culture Systems using Dynamic Mask Projection Photolithography

This article describes a nanoprecipitation method to synthesize polymer-based nanoparticles using diblock co-polymers. We will discuss the synthesis of diblock co-polymers, the nanoprecipitation technique, and potential applications.

Formulation of Diblock Polymeric Nanoparticles through Nanoprecipitation Technique

A protocol for nanoparticle tracking analysis (NTA) and high-throughput flow cytometry to evaluate polymeric gene delivery nanoparticles is described. NTA is utilized to characterize the nanoparticle particle size distribution and the plasmid per particle distribution. High-throughput flow cytometry enables quantitative transfection efficacy evaluation for a library of gene delivery biomaterials.

Evaluation of Polymeric Gene Delivery Nanoparticles by Nanoparticle Tracking Analysis and High-throughput Flow Cytometry

We describe the method of programming stem cells to overexpress therapeutic factors for angiogenesis using biodegradable polymeric nanoparticles. Processes described include polymer synthesis, transfecting adipose-derived stem cells in vitro, and validating the efficacy of programmed stem cells to promote angiogenesis in a murine hindlimb ischemia model.

Programming Stem Cells for Therapeutic Angiogenesis Using Biodegradable Polymeric Nanoparticles

Two adjacent fluids passing through a grooved microfluidic channel can be directed to form a sheath around a prepolymer core; thereby determining both shape and cross-section. Photoinitiated polymerization, such as thiol click chemistry, is well suited for rapidly solidifying the core fluid into a microfiber with predetermined size and shape.

Microfluidic Fabrication of Polymeric and Biohybrid Fibers with Predesigned Size and Shape

Learn mold-free fabrication of polymeric microneedles using photolithography for painless transdermal drug delivery. This precise UV polymerization method enables controlled microneedle dimensions without high temperatures.

Polymeric Microneedle Array Fabrication by Photolithography

Explore More Videos