Papers by Lawrence Kulinsky
Journal of Micro and Nano-Manufacturing, Feb 19, 2020
This special section of the ASME Journal of Micro-and Nano-Manufacturing contains selected papers... more This special section of the ASME Journal of Micro-and Nano-Manufacturing contains selected papers presented at the World Congress of Micro-and Nano-Manufacturing (WCMNM 2019) in Raleigh, NC. The congress is an annual international gathering of micromanufacturing experts organized by three societies-I2M2 (the International Institution on Micro-Manufacturing), IFMM (the International Forum on Micro-Manufacturing), and 4 M Association, representing primarily micro-manufacturing communities of Americas, Asia, and Europe, respectively.
Journal of Micro and Nano-Manufacturing, Jul 14, 2021
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ACS Applied Materials & Interfaces, Jul 24, 2020
Assembly of microdevices from constituent parts currently relies on slow serial steps via direct ... more Assembly of microdevices from constituent parts currently relies on slow serial steps via direct assembly processes such as pick-and-place operations. Template Electrokinetic Assembly (TEA), a guided, noncontact assembly process, is presented in this work as a promising alternative to serial assembly processes. To characterize the process and its implementation of electrokinetic, dielectrophoretic, and electro-osmotic phenomena, we conducted studies to examine the assembly of polymer microparticles at specific locations on glassy carbon interdigitated electrode arrays (IDEAs). The IDEAs are coated with a layer of lithographically patterned resist, so that when an AC electric field is applied to the IDEA, microparticles suspended in the aqueous solution are attracted to the open regions of the electrodes not covered by photoresist. Interplay between AC electro-osmosis and dielectrophoretic forces guides 1 and 5 μm diameter polystyrene beads to assemble in regions, or "wells", uncovered by photoresist atop the electrodes. It was discovered that AC electro-osmosis under an applied frequency of 1 kHz is sufficient to effectively agglomerate 1 μm beads in the wells, whereas a stepwise process involving the application of a 1 MHz signal, followed by a 1 kHz signal, is required for the positioning of 5 μm beads, which are mainly affected by dielectrophoretic forces. Permanent entrapment of the microparticles is then demonstrated via the electropolymerization process of the conducting polymer polypyrrole.
Biosensors and Bioelectronics, Oct 1, 2022
arXiv (Cornell University), Jul 22, 2021
As miniaturization of electrical and mechanical components used in modern technology progresses, ... more As miniaturization of electrical and mechanical components used in modern technology progresses, there is an increasing need for high-throughput and low-cost micro-scale assembly techniques. Many current micro-assembly methods are serial in nature, resulting in unfeasibly low throughput. Additionally, the need for increasingly smaller tools to pick and place individual microparts makes these methods cost prohibitive. Alternatively, parallel selfassembly or directed-assembly techniques can be employed by utilizing forces dominant at the micro and nano scales such as electro-kinetic, thermal, and capillary forces. However, these forces are governed by complex equations and often act on microparts simultaneously and competitively, making modeling and simulation difficult. The research in this paper presents a novel phenomenological approach to directed micro-assembly through the use of artificial intelligence to correlate micro-particle movement via dielectrophoretic and electro-osmotic forces in response to varying frequency of an applied non-uniform electric field. This research serves as a proof of concept of the application of artificial intelligence to create high yield low-cost micro-assembly techniques, which will prove useful in a variety of fields including micro-electrical-mechanical systems (MEMS), biotechnology, and tissue engineering.
Institution of Engineering and Technology eBooks, Jul 22, 2016
This review focuses on the advances in development of in-vivo microbiosensors in last five years.... more This review focuses on the advances in development of in-vivo microbiosensors in last five years. Many of the in-vivo microsensors that sometimes are loosely termed “biosensors,”but that don't contain biological recognition elements. For example, in-vivo real-time detection of nitric oxide, non-enzymatic electrochemical sensors using direct oxidation of glucose on the electrode surface that don't have biological recognition elements (such as enzymes, proteins, oligonucleotides),or boronic acid derivatives based fluorescence glucose sensors fall outside this survey.
Electrospinning is a versatile technique for production of nanofibers. However, it lacks the prec... more Electrospinning is a versatile technique for production of nanofibers. However, it lacks the precision and control necessary for fabrication of nanofiber-based devices. The positional control of the nanofiber placement can be dramatically improved using low-voltage near-field electrospinning (LV-NFES). LV-NFES allows nanofibers to be patterned on 2D and 3D substrates. However, use of NFES requires low working distance between the electrospinning nozzle and substrate, manual jet initiation, and precise substrate movement to control fiber deposition. Environmental factors such as humidity also need to be controlled. We developed a computer-controlled automation strategy for LV-NFES to improve performance and reliability. With this setup, the user is able to control the relevant sensor and actuator parameters through a custom graphic user interface application programmed on the C#.NET platform. The stage movement can be programmed as to achieve any desired nanofiber pattern and thickness. The nanofiber generation step is initiated through a software-controlled linear actuator. Parameter setting files can be saved into an Excel sheet and can be used subsequently in running multiple experiments. Each experiment is automatically video recorded and stamped with the pertinent real-time parameters. Humidity is controlled with ±3% accuracy through a feedback loop. Further improvements, such as real-time droplet size control for feed rate regulation are in progress.
Electrospinning is a versatile technique for production of nanofibers. However, it lacks the prec... more Electrospinning is a versatile technique for production of nanofibers. However, it lacks the precision and control necessary for fabrication of nanofiber-based devices. The positional control of the nanofiber placement can be dramatically improved using low-voltage near-field electrospinning (LV-NFES). LV-NFES allows nanofibers to be patterned on 2D and 3D substrates. However, use of NFES requires low working distance between the electrospinning nozzle and substrate, manual jet initiation, and precise substrate movement to control fiber deposition. Environmental factors such as humidity also need to be controlled. We developed a computer-controlled automation strategy for LV-NFES to improve performance and reliability. With this setup, the user is able to control the relevant sensor and actuator parameters through a custom graphic user interface application programmed on the C#.NET platform. The stage movement can be programmed as to achieve any desired nanofiber pattern and thickness. The nanofiber generation step is initiated through a software-controlled linear actuator. Parameter setting files can be saved into an Excel sheet and can be used subsequently in running multiple experiments. Each experiment is automatically video recorded and stamped with the pertinent real-time parameters. Humidity is controlled with ±3% accuracy through a feedback loop. Further improvements, such as real-time droplet size control for feed rate regulation are in progress.
Biomicrofluidics, May 1, 2022
Nowadays, centrifugal microfluidic platforms are finding wider acceptance for implementing point-... more Nowadays, centrifugal microfluidic platforms are finding wider acceptance for implementing point-of-care assays due to the simplicity of the controls, the versatility of the fluidic operations, and the ability to create a self-enclosed system, thus minimizing the risk of contamination for either the sample or surroundings. Despite these advantages, one of the inherent weaknesses of CD microfluidics is that all the sequential fluidic chambers and channels must be positioned radially since the centrifugal force acts from the center of the disk outward. Implementation of schemes where the liquid can be rerouted from the disk periphery to the disk center would significantly increase the utility of CD platforms and increase the rational utilization of the real estate on the disk. The present study outlines a novel utilization of elastic membranes covering fluidic chambers to implement inward pumping whereby the fluid is returned from the disk periphery to the center of the disk. When the disk revolves at an angular velocity of 3600 rpm, liquid enters the chamber covered by the elastic membrane. This membrane is deflected upward by liquid, storing energy like a compressed spring. When the angular velocity of the disk is reduced to 180 rpm and thus the centrifugal force is diminished, the elastic membrane pushes the liquid from the chamber inward, closer to the center of the disk. There are two channels leading from the elastic membrane-covered reservoir—one channel has a higher fluidic resistance and the other (wider) has a lower fluidic resistance. The geometry of these two channels determines the fluidic path inward (toward the center of the disk). Most of the liquid travels through the recirculating channel with lower resistance. We demonstrated an inward pumping efficiency in the range of 78%–89%. Elastic membrane-driven inward pumping was demonstrated for the application of enhanced fluid mixing. Additionally, to demonstrate the utility of the proposed pumping mechanism for multi-step assays on the disk, we implemented and tested a disk design that combines plasma separation and inward pumping.
Microfluidics and Nanofluidics, 2016
many fractions as there are immiscible liquids of different densities in the tuning chamber. The ... more many fractions as there are immiscible liquids of different densities in the tuning chamber. The presented work also demonstrates the use of polybutene in sealing fluidic chambers to improve heating efficiency and to minimize evaporation during thermal cycling required for applications such as PCR amplification. Finally, the use of polybutene as a stationary liquid phase in droplet production on a spinning disc is demonstrated.
Journal of Micromechanics and Microengineering, May 29, 2019
Controlled bidirectional flow by AC electroosmotic means is achieved using asymmetric coplanar an... more Controlled bidirectional flow by AC electroosmotic means is achieved using asymmetric coplanar and high-aspect-ratio glassy carbon electrodes and without the involvement of moving elements. The forward and backward fluidic propulsion is the result of hydrodynamic channeling of the fluid in a microfluidic device. The asymmetric coplanar electrodes were fabricated by photolithographic patterning of SU-8 photoresist, followed by pyrolysis at 900 °C. Morphological characterization of the carbon structures was carried out by SEM and confocal microscopy. Then, Raman and EDX spectroscopies confirmed that the resulting carbon material is appropriate for electrokinetic applications. A finite element analysis was carried out to study the flow development by AC electroosmosis. Electrode arrays of three different asymmetry ratios (60 µm:20 µm, 80 µm:20 µm, and 100 µm:20 µm) were fabricated and tested. Fluid velocity was measured for an applied bias in the 2–20 V PP amplitude range, and in the 1 kHz to 200 MHz frequency range. Overall maximum measured forward and reverse fluid velocities were 28.59 µm s−1 and 338 µm s−1, respectively. On an additional set of devices with the same asymmetry ratios, a second photolithography step was utilized to produce high-aspect-ratio microposts on top of the coplanar electrodes to study the effect of high electrode contact surface to generate bidirectional flow. Using the same amplitude and frequency ranges as for planar structures in experimental testing, the overall maximum measured velocities were 9.23 µm s−1 and 90.66 µm s−1 for the forward and reverse regimes, respectively. In contrast to the planar electrodes, microposts-containing electrodes had more balanced velocity magnitudes between reverse and forward flows as the asymmetry ratio increases. In this case, the use of this electrode topology can be useful when symmetry of the forward and backward flow is more important than the magnitude of the volumetric flow rate.
Sensors and Actuators B-chemical, Jul 1, 2023
Micromachines
Fabrication of micro- and nanofibers are critical for a wide range of applications from microelec... more Fabrication of micro- and nanofibers are critical for a wide range of applications from microelectronics to biotechnology. Alginate microfibers with diameters of tens to hundreds of microns play an important role in tissue engineering and fibers of these diameters are impossible to fabricate via electrospinning and can only be produced via fluidic spinning. Typically, microfluidic spinning based on photopolymerization produces fibers that are not easily dissolvable, while fluidic spinning with chemical cross-linking employs complex setups of microfabricated chips or coaxial needles, aimed at precise control of the fiber diameter; however, fluidic spinning introduces significant cost and complexity to the microfluidic setup. We demonstrate immersed microfluidic spinning where a calcium alginate microfiber is produced via displacement of alginate solution through a single needle that is immersed in a cross-linking bath of calcium chloride solution. The resulting diameter of the fiber ...
Sensors
Numerous immunoassays have been successfully integrated on disc-based centrifugal platforms (CDs)... more Numerous immunoassays have been successfully integrated on disc-based centrifugal platforms (CDs) over the last 20 years. These CD devices can be used as portable point-of-care (POC) platforms with sample-to-answer capabilities where bodily fluids such as whole blood can be used as samples directly without pre-processing. In order to use whole blood as a sample on CDs, centrifugation is used to separate red blood cells from plasma on CDs. There are several techniques for using specific fluidic patterns in the centrifugal fluidic network, such as reciprocation, that enhances the sensitivity of the immunoassays, including those using microarray antigen membranes. Present work demonstrates, for the first time, simultaneous integration of blood plasma separation (BPS) and reciprocation on the CD platform. The integrated design allows plasma that is separated from the red blood cells in a sedimentation chamber to flow into the reciprocation chamber via a narrow connecting channel of 0.5 ...
Electrospinning is a versatile technique for production of nanofibers. However, it lacks the prec... more Electrospinning is a versatile technique for production of nanofibers. However, it lacks the precision and control necessary for fabrication of nanofiber-based devices. The positional control of the nanofiber placement can be dramatically improved using low-voltage near-field electrospinning (LV-NFES). LV-NFES allows nanofibers to be patterned on 2D and 3D substrates. However, use of NFES requires low working distance between the electrospinning nozzle and substrate, manual jet initiation, and precise substrate movement to control fiber deposition. Environmental factors such as humidity also need to be controlled. We developed a computer-controlled automation strategy for LV-NFES to improve performance and reliability. With this setup, the user is able to control the relevant sensor and actuator parameters through a custom graphic user interface application programmed on the C#.NET platform. The stage movement can be programmed as to achieve any desired nanofiber pattern and thickne...
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Papers by Lawrence Kulinsky