Polydimethylsiloxane Prepolymer Research Articles

PLA 3D Printing as a Straightforward and Versatile Fabrication Method for PDMS Molds.

3D printing is gaining traction in research and development as a way to quickly, cheaply, and easily manufacture polydimethylsiloxane (PDMS) molds. The most commonly used method is resin printing, which is relatively expensive and requires specialized printers. This study shows that polylactic acid (PLA) filament printing is a cheaper, more readily available alternative to resin printing, that does not inhibit the curing of PDMS. As a proof of concept, a PLA mold for PDMS-based wells was designed, and 3D printed. We introduce an effective method to smooth the printed PLA mold, based on chloroform vapor treatment. After this chemical post-processing step, the smoothened mold was used to cast a ring of PDMS prepolymer. The PDMS ring was attached to a glass coverslip after oxygen plasma treatment. The PDMS-glass well showed no leakage and was well suited to its intended use. When used for cell culturing, monocyte-derived dendritic cells (moDCs) showed no morphological anomalies, as tested by confocal microscopy, nor did they show an increase in cytokines, as tested using ELISA. This underlines the versatility and strength of PLA filament printing and exemplifies how it can be valuable to a researcher's toolset.

Parallelization of Microfluidic Droplet Junctions for Ultraviscous Fluids (Small 48/2022)

Ultraviscous Fluids In article number 2205001 by Seungwoo Lee and co-workers, a 2D branched droplet microfluidic device for ultraviscous fluid is designed and fabricated. Parallelly arranged 64 T-junctions compose the droplet microfluidic device. Each junction is specifically designed based on hydraulic resistance. Through the device, the fluid with a viscosity of 3.5 Pa.s (i.e., polydimethylsiloxane prepolymer) can be fabricated as monodispersed droplets. The production rate is ≈330 000 droplets per hour and the generated droplets have a 2∼3% coefficient of variation.

Direct measurement of vorticity using tracer particles with internal markers

Current experiment techniques for vorticity measurement suffer from limited spatial and temporal resolution to resolve the small-scale eddy dynamics in turbulence. In this study, we develop a new method for direct vorticity measurement in fluid flows based on digital inline holography (DIH). The DIH system utilizes a collimated laser beam to illuminate the tracers with internal markers and a digital sensor to record the generated holograms. The tracers made of the polydimethylsiloxane prepolymer mixed with internal markers are fabricated using a standard microfluidic droplet generator. A rotation measurement algorithm is developed based on the 3D location reconstruction and tracking of the internal markers and is assessed through synthetic holograms to identify the optimal parameter settings and measurement range (e.g., rotation rate from 0.3 to 0.7 rad/frame under numerical aperture of imaging of 0.25). Our proposed method based on DIH is evaluated by a calibration experiment of single tracer rotation, which yields the same optimal measurement range. Using von Kármán swirling flow setup, we further demonstrate the capability of the approach to simultaneously measure the Lagrangian rotation and translation of multiple tracers. Our method can measure vorticity in a small region on the order of 100 µm or less and can be potentially used to quantify the Kolmogorov-scale vorticity field in turbulent flows.

Piezoresistive anisotropy in conductive silicon rubber/multi-walled carbon nanotube/nickel particle composites via alignment of nickel particles

Conventional piezoresistive sensors of flexible conductive polymer composites (FCPC) are mostly isotropic because of the weak controllable fabrication strategies. In this study, a facile strategy was introduced to fabricate the polydimethylsiloxane (PDMS)/multi-walled carbon nanotubes (CNT)/aligned nickel particles (Ni) composites under a low magnetic field. The PDMS pre-polymer firstly mixed with CNT and Ni particles with ultrasonic and solvent assistant, and then cured under a magnetic field with a magnetic flux density of 75 mT to form the composites. Because of the alignment of Ni particles, the PDMS/CNT/align-Ni composites exhibited obviously electrical, mechanical and piezoresistive anisotropy. Specifically, the compression modulus of the composites with 0.23 vol% CNTs and 3.93 vol% Ni particles was ∼4.93 and ∼3.66 MPa at the direction parallel to (X direction) and vertical to the alignment direction of Ni particles (Y direction), respectively. The anisotropic index of the electrical conductivity could reach 2.6 × 105 in the PDMS/CNT/aligned-Ni composites containing 0.23 vol% CNT and 3.37 vol% Ni particles. Furthermore, the PDMS/CNT/aligned-Ni composites showed a negative piezoresistive effect at X direction and a positive piezoresistive effect at Y direction.

Wet‐Adhesive Elastomer for Liquid Metal‐Based Conformal Epidermal Electronics

AbstractWearable electronics are increasingly used in health monitoring and treatment in different conditions. However, few devices can adhere conformally to the skin after sports and showers (sweating, deformation, friction). Here, a facile method is presented by providing a metal‐polymer conductor (MPC) made with polyethylene glycol (PEG) blended polydimethylsiloxane (PDMS) based adhesive (PPA) that encapsulates gallium‐based liquid metal alloy circuits as epidermal electronics. Adding PEG into PDMS prepolymer can result in a softer and wet‐adhesive elastomer that can bear larger deformation than PDMS itself. The soft and adhesive electronics can adhere to the skin conformally for more than 2 d. It has been demonstrated that these electronics can meet the needs of motion detection, electrophysiological signal detection and skin wound healing during a 48 h wearing with sports and shower. It is expected that the wet‐adhesive electronic with excellent biosafety can be widely used and solve existing problems in medical adhesives and human–machine interfaces.

Noncovalent reversible binding-enabled facile fabrication of leak-free PDMS microfluidic devices without plasma treatment for convenient cell loading and retrieval

The conventional approach for fabricating polydimethylsiloxane (PDMS) microfluidic devices is a lengthy and inconvenient procedure and may require a clean-room microfabrication facility often not readily available. Furthermore, living cells can't survive the oxygen-plasma and high-temperature-baking treatments required for covalent bonding to assemble multiple PDMS parts into a leak-free device, and it is difficult to disassemble the devices because of the irreversible covalent bonding. As a result, seeding/loading cells into and retrieving cells from the devices are challenging. Here, we discovered that decreasing the curing agent for crosslinking the PDMS prepolymer increases the noncovalent binding energy of the resultant PDMS surfaces without plasma or any other treatment. This enables convenient fabrication of leak-free microfluidic devices by noncovalent binding for various biomedical applications that require high pressure/flow rates and/or long-term cell culture, by simply hand-pressing the PDMS parts without plasma or any other treatment to bind/assemble. With this method, multiple types of cells can be conveniently loaded into specific areas of the PDMS parts before assembly and due to the reversible nature of the noncovalent bonding, the assembled device can be easily disassembled by hand peeling for retrieving cells. Combining with 3D printers that are widely available for making masters to eliminate the need of photolithography, this facile yet rigorous fabrication approach is much faster and more convenient for making PDMS microfluidic devices than the conventional oxygen plasma-baking-based irreversible covalent bonding method.

Synergistic enhancement of thermal conductivity in thermal interface materials by fabricating3D‐BN‐ZnOscaffolds

AbstractThree‐dimensional boron nitride/zinc oxide (3D‐BN‐ZnO) scaffolds were prepared by the ice‐templating method, in which ZnO particles were in situ formed by sintering. Then, polydimethylsiloxane (PDMS)/3D‐BN‐ZnO composites were fabricated via vacuum infiltration of PDMS prepolymer into the scaffolds and curing. Compared with the composite prepared by simple blending, the thermal conductivity of the composite prepared based on the ice‐templating method is much higher due to the excellent orientation of hexagonal boron nitride (hBN) sheets. Based on the same content of hBN sheets, the further introduction of 2.7 wt% ZnO particles formed in situ by sintering could promote the thermal conductivity of the composite to the value of 1.45 W m−1 K−1, which is 70.6% higher than that of the PDMS/3D‐BN composite. In addition, compared with the PDMS/3D‐BN composite containing more hBN sheets, the PDMS/3D‐BN‐ZnO composite with 2.7 wt% ZnO particles possesses fewer fillers but higher thermal conductivity. It suggests that ZnO particles could synergistically improve the thermal conductivity. As revealed from the morphology of the composites, many ZnO particles are located between hBN sheets and thus construct thermally conductive paths. This study provides a new strategy for the design of thermal interface materials with high thermal conductivity.

Influence of pore morphologies on the mechanical and tribo-electrical performance of polydimethylsiloxane sponge fabricated via commercial seasoning templates

This work demonstrated the influence of pore morphologies on the mechanical behavior and tribo-electrical performance of fabricated polydimethylsiloxane (PDMS) sponge. Commercial seasonings with different 3D geometric shapes were used as a sacrificial template to control the pore structure of the PDMS sponge. The result indicated that the softest PDMS sponge was molded by using a sodium chloride (NaCl) crystal template, as indicated by the lowest compressive modulus value. Then, P(VDF–HFP) was incorporated into PDMS prepolymer in order to enhance the charge generation characteristic of PDMS. Besides, the composite 3D structure was revealed using synchrotron radiation X-ray tomographic microscopy (SRXTM). Interpretation from the SRXTM result confirmed that the porous structure had different pore shapes, i.e., an octahedral-like shape and a circular-like shape in a particular sponge. By pairing the composite PDMS sponge with an aluminum (Al) plate for the triboelectric nanogenerator (TENG), the maximum electrical outputs of ~29.9 V and ~0.56 μA for voltage and current, respectively, were detected with loading 50 wt% of P(VDF – HFP). The presented TENG was applied successfully for sensing basic human activities practically, which demonstrated potential applications in wearable electronics.

Elastic Photonic Microcapsules Containing Colloidal Crystallites as Building Blocks for Macroscopic Photonic Surfaces.

Colloidal crystals develop structural colors through wavelength-selective diffraction. Recently, a granular format of colloidal crystals has emerged as building blocks to construct macroscopic photonic surfaces or architectures with high reconfigurability through the secondary assembly. Here, we design elastic photonic microcapsules containing colloidal crystallites along the inner wall as a building block. Water-in-oil-in-water double-emulsion templates are microfluidically prepared to have an aqueous dispersion of polystyrene particles in the inner droplet and polydimethylsiloxane prepolymers in the shell. Colloidal particles are enriched in the presence of depletant and salt by osmotic compression, with the crystallization at the inner interface by depletion attraction. The number of nucleation sites depends on the rate of the enrichment, which enables control over the size and surface coverage of the crystallites with osmotic conditions. The enrichment is ceased by transferring the droplets into an isotonic solution, and the oil shell is cured to form an elastic membrane. As the elastic microcapsules have a large void in the core, they are deformable without structural damage in the crystallites. Therefore, the microcapsules can be closely packed to form macroscopic surfaces while achieving a high quality of structural colors with a collection of crystallites aligned along the flattened membrane.

3D Printing Silicone Elastomer for Patient-Specific Wearable Pulse Oximeter.

Commercial pulse oximeters are used clinically to measure heart rate and blood oxygen saturation and traditionally made from rigid materials. However, these devices are unsuitable for continuous monitoring due to poor fit and mechanical mismatch. Soft materials that match the elastic properties of biological tissue provide improved comfort and signal-to-noise but typically require molding to manufacture, limiting the speed and ease of customizing for patient-specific anatomy. Here, freeform reversible embedding (FRE) 3D printing is used to create polydimethylsiloxane (PDMS) elastomer cuffs for use on the hand and foot. FRE enables printing liquid PDMS prepolymer in 3D geometries within a sacrificial hydrogel bath that provides support during cure. This serves as proof-of-concept for fabricating patient-specific pulse oximeters with pressure sensing, termed P3 -wearable. A sizing analysis establishes dimensional accuracy of FRE-printed PDMS compared to anatomical computer-aided design models. The P3 -wearable successfully outputs photoplethysmography (PPG) and pressure amplitude signals wirelessly to a tablet in real time and the PPG is used to calculate heart rate, blood oxygen content, and activity state. The results establish that FRE printing of PDMS can be used to fabricate patient-specific wearable devices and measure heart rate and blood oxygenation on par with commercial devices.

Optimization of micromilled channels for microfluidic applications using gas-blowing-assisted PDMS coating

Micromilling is a flexible, inexpensive and rapid prototyping technique for polymer microfluidic devices. However, the applications of microfluidic devices fabricated by micromilling have been compromised by their poor surface quality. In this study, we demonstrated a gas-blowing-assisted (GBA) polydimethylsiloxane (PDMS) coating that is used to reduce the surface roughness of micromilled channels, yielding optical grade channel walls while simultaneously offering high flexibility in channel dimensions and morphology by controlling the coating parameters. In this method, a thin layer of PDMS is coated on the engraved substrate, and then a computer numerical control (CNC)-guided gas-blowing is used to selectively remove surplus PDMS prepolymer in channels, which results in a thin residual and smooth PDMS coating on the walls of channels. With this GBA PDMS coating, the channel surface roughness of below 8 nm could be achieved without the need of advanced polishing equipment or procedures. Furthermore, this method has the capability to fabricate non-rectangular microchannels with different shapes in cross-section depending on the process parameters, which benefits microvascular research and tissue engineering.

Grafting Robust Thick Zwitterionic Polymer Brushes via Subsurface-Initiated Ring-Opening Metathesis Polymerization for Antimicrobial and Anti-Biofouling.

In the present work, high-thickness zwitterionic polymer brushes based on imidazolium salts were successfully grafted via a novel subsurface-initiated ring-opening metathesis polymerization (subsurface-initiated ROMP) from polydimethylsiloxane (PDMS), and their antifouling performance was evaluated in detail. First, an initiator-embedded PDMS was prepared via copolymerization of PDMS prepolymer and ROMP initiator, and then zwitterionic polymer brushes were grafted via subsurface-initiated ROMP from surface to subsurface of the PDMS due to the implanted ROMP initiator. Results from a series of characterization methods such as infrared spectroscopy, X-ray photoelectron spectroscopy, contact angle, and atomic force microscopy proved the zwitterionic polymer brushes' successful grafting. The grafting thickness of zwitterionic polymer brushes via subsurface-initiated ROMP can reach the micron scale, and the as-prepared zwitterionic polymer based surfaces showed good lubricating properties compared to traditional surface-initiated ROMP, which hints that polymer brushes can be grafted not only on the surface but also on the subsurface of PDMS. The protein adhesion test and biofouling assay of zwitterionic polymer brushes were tested in the laboratory, and the results indicated that the zwitterionic polymer-functionalized PDMS can effectively resist the adhesion of bovine serum albumin and algae (Porphyridium and Dunaliella) and has good anti-bacterial activity against both Escherichia coli and Staphylococcus aureus.

Paper-Based All-in-One Origami Microdevice for Nucleic Acid Amplification Testing for Rapid Colorimetric Identification of Live Cells for Point-of-Care Testing.

We report herein the colorimetric identification of live cells based on a nucleic acid amplification testing (NAAT) methodology using an all-in-one origami paper microdevice integrated with DNA purification, loop-mediated isothermal amplification (LAMP), and on-site colorimetric detection. First, origami paper was partially embossed to create microchannel networks and chambers. Subsequently, hydrophobic polydimethylsiloxane prepolymer was coated onto the embossed paper to stabilize the structures on paper and provide fluid barriers. The paper microdevice was composed of splitting, purification, wicking, reaction, and dye pads folded alternatively to accomplish sensitive and specific NAAT. For the viability assay, propidium monoazide (PMA) was employed to penetrate dead cells and form covalent bonds with necrotic cell DNA; thus, amplification can be solely performed with DNA obtained from live bacterial cells. Purification functionality was implemented into the microdevice using chitosan to electrostatically capture DNA. Herein, methylene blue, which is typically used for electrochemical detection, is introduced for the first time for colorimetric detection of LAMP amplicons. This origami paper microdevice was successfully applied to determine the viability of foodborne pathogens, such as Escherichia coli O157:H7 and Salmonella spp., in which amplification was performed for 30 min followed by the execution of the colorimetric method for 10 min, thereby demonstrating tremendous potential for multiplexing and versatility for point-of-care applications. The introduced origami paper microdevice could be an attractive substitute as an instantaneous and convenient screening tool for the identification of viable pathogens in the control and monitoring of foodborne outbreaks in low-resource environments.

The Fabrication of Nanostructures on Polydimethylsiloxane by Laser Interference Lithography.

We report a method for fabricating periodic nanostructures on the surface of polydimethylsiloxane (PDMS) using laser interference lithography. The wave-front splitting method was used for the system, as the period and duty cycle can be easily controlled. Indium tin oxide (ITO) glass reveals favorable characteristics for controlling the standing waves distributed in the vertical direction, and was selected as the rigid substrate for the curing of the PDMS prepolymer, photoresist spin coating, and exposure processes. Periodic nanostructures such as gratings, dot, and hole arrays were prepared. This efficient way of fabricating large area periodic nanoscale patterns will be useful for surface plasmonic resonance and wearable electronics.

Culturing melanocytes and fibroblasts within three-dimensional macroporous PDMS scaffolds: towards skin dressing material.

In the present study, we propose a platform for topical wound dressing material using a polydimethylsiloxane (PDMS) scaffold in order to enhance the skin healing process. In vitro co-culture assessment of epidermal-origin mouse B16-F10 melanocyte cells and mouse L929 fibroblast cells in three-dimensional polymeric scaffolds has been carried out towards developing bio-stable, interconnected, highly macroporous, PDMS based tissue-engineered scaffolds, using the salt leaching method. To determine a suitable ratio of salt to PDMS pre-polymer in the scaffold, two different samples with ratios 2:1 and 3:1 [w/w], were fabricated. Effective pore sizes of both scaffolds were observed to lie in the desirable range of 152-165μm. In addition, scaffolds were pre-coated with collagen and investigated as a podium for culturing the chosen cells (fibroblast and melanocyte cells). Experimental results demonstrate not only a high proliferative potential of the skin tissue-specific cells within the fabricated PDMS based scaffolds but also confirm the presence of several other essential attributes such as high interconnectivity, optimum porosity, excellent mechanical strength, gaseous permeability, promising cell compatibility, water absorption capability and desired surface wettability. Therefore, scaffolds facilitate a high degree of cellular adhesion while providing a microenvironment necessary for optimal cellular infiltration and viability. Thus, the outcomes suggest that PDMS based macroporous scaffold can be used as a potential candidate for skin dressing material. In addition, the fabricated PDMS scaffolds may also be exploited for a plethora of other applications in tissue engineering and drug delivery.

Preparation of superhydrophobic porous coating film with the matrix covered with polydimethylsiloxane for oil/water separation

In this work, an organic coating film was designed to have a porous microstructure together with a rough surface, and its matrix was covered with a low surface energy layer, so that it can be employed for oil/water separation based on its superhydrophobicity and superoleophilicity. First, a mixture solution of poly(styrene-block-butadiene-block-styrene) (SBS) and polydimethylsiloxane (PDMS) prepolymer was sprayed onto stainless steel mesh in a non-solvent vapor atmosphere of ethanol. After solvent evaporation, a porous coating film has been obtained. The film matrix was formed from SBS to have a nodular-microstructure, which was covered by the highly flexible PDMS prepolymer. Then, the PDMS prepolymer was cured to cover the nodular microstructure at 60 °C, which was chosen to be far below the glass transition temperature of polystyrene block of SBS in order to maintain the formed nodular microstructure. The microstructures of the obtained coating films were carefully characterized and analyzed. Water and oil contact angles on the coating films were measured to indicate their wetting properties of superhydrophobicity and superoleophilicity. The oil diffusion speed along the coating film and the oil swelling behavior were examined to suggest the advantages of the covering PDMS layer. The coating films have been employed for oil/water separation through self gravity-driven filtration, where oil could penetrate the coating film automatically while water retained. The oil separation rate was found to be higher than 99.0% and the flux was estimated to be greater than 162 L∙h−1 m−2. Moreover, the cycling tests suggest the satisfactory reusability of the coating film, implying its potential applications in oily wastewater treatment or oil spill recovery.

Biomimetic Cilia‐Patterned Rubber Electrode Using Ultra Conductive Polydimethylsiloxane

AbstractIn this paper, a biomimetic cilia‐patterned flexible electrode using ultra conductive polydimethylsiloxane (PDMS) is presented. Due to the flexibility and cilia patterns, the developed electrode can have conformal contact with the human skin without interruptions of hair and rough skin. The conductive PDMS is prepared by mixing PDMS prepolymer and curing agent with Ag particles at different ratios. The performance of the best composite‐made ciliated electrode is evaluated under different skin‐like physical environments, and compared to the nonciliated flat electrode. For a typical flat electrode, hair and rough surface of the human skin disturb electrical contact, increasing contact impedance, whereas flexible ciliary structures of the proposed electrode show significantly improved conductivity passing through the furs to penetrate well into the gap on the alloyed skin, thus increasing the contact areas. Furthermore, bio‐signal measurement using rigid metal electrodes suffers from motion artifacts causing signal errors due to bodily movement, which is remarkably addressed by ciliated flexible electrode. Therefore, the proposed electrode is applied to recording electrocardiography signal and compared with signal measured with conventional metal electrode, which showed about 20% enhancement than that of metal counterpart in identifying electrical activity of heart muscle of a person, as point‐of‐care clinical applications.

Cellulose Nanofiber/Carbon Nanotube Conductive Nano-Network as a Reinforcement Template for Polydimethylsiloxane Nanocomposite.

Both cellulose nanofiber (CNF) and carbon nanotube (CNT) are nanoscale fibers that have shown reinforcing effects in polymer composites. It’s worth noting that CNF and CNT could form a three-dimensional nano-network via mixing and vacuum filtration, which exhibit excellent mechanical strength and electrical conductivity. In this study, the developed CNF/CNT film was applied as a nano-network template and immersed into polydimethylsiloxane (PDMS) solutions. By controlling the immersed polydimethylsiloxane pre-polymer concentration, the PDMS/CNF/CNT nanocomposite with various PDMS contents were fabricated after a curing process. Morphological images showed that the CNF/CNT nano-network was well-preserved inside the PDMS, which resulted in significantly improved mechanical strength. While increasing the PDMS content (~71.3 wt %) gave rise to decreased tensile strength, the PDMS-30/CNF/CNT showed a fracture strain of 7.5%, which was around seven fold higher than the rigid CNF/CNT and still kept a desirable strength—Young’s modulus and conductivity of 18.3 MPa, 805 MPa, and 0.8 S/cm, respectively. Therefore, with the enhanced mechanical properties and the electrical conductivity, the prepared PDMS/CNF/CNT composite films may offer promising and broad prospects in the field of flexible devices.

Reverse hydrophobic PDMS surface to hydrophilic by 1‐step hydrolysis reaction

Hydrophilic modification on the surface of polymer polydimethylsiloxane (PDMS) material is a key step for its application in biomaterial, bioengineering, and so on. In this article, a novel and effective method was proposed to reverse hydrophobic surface to hydrophilic by 1‐step hydrolysis of Si―O bond to produce hydrophilic hydroxyl group. The hydrophilizing reagent 2‐(trimethylsiloxy) ethyl methacrylate (TMSEMA) was used during the copolymerization of polydimethylsiloxane prepolymer (DMS U21). The prepared PDMS film was subjected to 1‐step surface hydrophilic reversal treatment using KOH solution to produce hydroxyl groups on the surface. The contact angle, attenuated total reflection Fourier transform infrared spectra, and equilibrium water content (EWC) measurements were conducted on PDMS films. The results showed that TMSEMA content had no obvious impact on the contact angle and EWC value of untreated PDMS. After reversal treatment, the contact angle decreased from 94° to 15°, and the EWC value increases to 10% when the TMSEMA content was 15 wt%. The spectrum proved that the reverse reaction produced hydroxyl and carboxylate on the surface. The hydrophilic stability, surface morphology, and protein adsorption properties of PDMS film were also investigated. This study can provide new ideas and further reference for improving the hydrophilicity of PDMS surface.

IR-Compatible PDMS microfluidic devices for monitoring of enzyme kinetics

Coupling infrared (IR) spectroscopy to microfluidic devices provides a powerful tool for characterizing complex chemical and biochemical reactions. Examples of microfluidic devices coupled with infrared spectroscopy have been limited, however, largely due to the difficulties associated with fabricating systems in common infrared transparent materials like CaF2. Recent reports have shown that polydimethylsiloxane (PDMS) can be used as an IR transparent substrate when fabricated with thin layers. The use of soft lithography with PDMS expands the library of possible designs that can be achieved for IR measurements in microfluidics. In initial reports with thin PDMS, the target analytes were small molecules; however, IR spectroscopy offers a powerful tool to study protein structure and reactions. Here, a PDMS microfluidic device compatible with IR spectroscopy was fabricated by means of spin-coating of PDMS pre-polymer to obtain thin PDMS microfluidic features. The device was comprised of only PDMS and IR absorption of PDMS was significantly minimized due to the thickness (∼40 μm) of the PDMS layer. The use of thin PDMS allowed for measuring the amide I and II vibrational bands of proteins that have been difficult to measure in other microfluidic devices. To demonstrate the power of the system, the microfluidic device was successfully used to measure the enzyme kinetics as one class of important biochemical reactions with broad use in a variety of fields from medicine to biotechnology. As a model, the reaction of glucose oxidase with glucose was tracked by following the formation of gluconic acid. Michaelis-Menten kinetics from the device were compared with bulk solution measurements and found to be in good agreement.