This work was sponsored by the Ministry of Science and Technology, Taiwan, under grant numbers MOST 104-2221-E-241-001-MY3 and MOST 105-2627-B-005-002.

1. Experimental Chip Module
<ol>
	<li>Fabricate the indium tin oxide (ITO) electrode chip by photolithography and chemical wet etching processes
	<ol>
		<li>Obtain an ITO substrate (370 mm x 480 mm x 0.5 mm (L x W x H)) with a 2,600 &#197; ITO layer commercially (See Materials List). Slice the ITO substrate to the dimensions of 90 mm x 90 mm x 0.5 mm with a glass cutter for the ITO electrode patterning process in a 4 inch aligner.</li>
		<li>Use an ultrasonic cleaner to clean the ITO glass with acetone and then with deionized water, for 15 min each. Dry the ITO glass with clean dry air.</li>
		<li>Dispense 5 ml of positive photoresist solution onto the surface of the ITO glass.</li>
		<li>Use spin coater at 500 x g for 30 sec to produce a uniform photoresist layer. Then bake on a hotplate at 90 &#176;C for 5 min to drive off excess solvent in the photoresist.</li>
		<li>Expose the ITO glass to 14 mW of ultraviolet light at 436 nm for 3.1 sec through a film photomask with the designed pattern (See Materials List).</li>
		<li>Immerse the sample in 60 ml development solution at 23 &#176;C for 30 sec to develop the patterned routes. Then bake on a hotplate at 120 &#176;C for 10 min to harden the photoresist and improve photoresist adhesion.</li>
		<li>Immerse the sample for 3 min in 60 ml etching solution at 80 &#176;C to etch the unprotected ITO layer.</li>
		<li>Immerse the sample for 1 min in 60 ml acetone to remove photoresist on surface of the ITO glass.</li>
		<li>Slice the ITO glass into the dimensions of 62 mm x 35 mm for the experimental ITO electrode chip (Figure 1) with a glass cutter.</li>
	</ol>
	</li>
</ol>
<img alt="Figure 1" src="/files/ftp_upload/54575/54575fig1.jpg" /> 
Figure 1: ITO electrode chip. The fabricated ITO chip with 8 pairs of electrode-patterned routes is shown. There are 15 electrodes measuring 2 mm x 8 mm at the side edge, and the central two routes share the same electrode. The distance between each pair of electrode fingers in a test well is 7 mm. <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/54575/54575fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<ol start="2">
	<li>Construct the experimental chip module
	<ol>
		<li>Clean the commercial 8-well silicone array with an ultrasonic cleaner as shown in Figure 2 with detergent, then deionized water, then 95% ethanol, and then deionized water, for 15 min each.</li>
		<li>Dry the 8-well silicone array by blowing clean dry air.</li>
		<li>Press the 8-well silicone array into the ITO chip in order to form the experimental chip module (Figure 3). Tightly bind the silicone array and ITO chip.</li>
	</ol>
	</li>
</ol>
<img alt="Figure 2" src="/files/ftp_upload/54575/54575fig2.jpg" /> 
Figure 2: Silicone well array. The commercial 8-well silicone array can hold 8 tested samples simultaneously. The size of each well is 11 mm x 8 mm x 8.5 mm (L x W x H). <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/54575/54575fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" src="/files/ftp_upload/54575/54575fig3.jpg" /> 
Figure 3: Experimental chip module. The ITO electrode chip is attached with the 8-well silicone array to form the experimental chip module. The adhesion between the silicone array and the ITO chip is strong. Therefore, the silicone array and the ITO chip can bond together for use without any adhesive substance. <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/54575/54575fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
2. Impedance Measurement
<ol>
	<li>Connect the personal computer, lock-in amplifier, and switch relay to form the impedance readout module as shown in Figure 4.</li>
</ol>
<img alt="Figure 4" src="/files/ftp_upload/54575/54575fig4.jpg" /> 
Figure 4: Schematic of the impedance-based apparatus. The lock-in amplifier, switch relay, and personal computer comprise the impedance readout module. The commercial phase-sensitive lock-in amplifier is used to send and extract the electrical signals. The homemade switch relay circuit connecting various ITO chips is used to specify which well and which ITO chip to be tested. A total of 6 chips can be connected to the switch relay specifying 48 samples in a time sharing manner. The real-time in-phase resistance and the signal phase shift of the tested solution are recorded continuously on a personal computer for the whole evaporation process. <a href="https://www-jove-com.bdigitaluss.remotexs.co/files/ftp_upload/54575/54575fig4large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<ol start="2">
	<li>Put the experimental chip module into the socket of the switch relay.</li>
	<li>Input parameters in the computer program. Input the signal frequency (1 kHz), the specified well number (0-7), the execution cycle (100), and the filename (HA).</li>
</ol>
3. Evaporation Experiments
<ol>
	<li>Prepare four 2.5 ml hyaluronic acid solutions at 0, 0.05, 0.5 and 1 w/v% in water. Place each 2.5 ml sample solution in a vial measuring 14.75 mm x 45 mm x 8 mm (O.D. x H x I.D.).</li>
	<li>For each solution, add 0.5 ml sample solution to a single well of the ITO chip module.</li>
	<li>Weigh and record the initial weight of each vial by the electronic balance machine.</li>
	<li>Execute the computer program to automatically measure and record the real-time in-phase resistance and the signal phase shift of specified wells on the ITO chip.</li>
	<li>Start the evaporation experiments simultaneously in the same place by both the weighing method and impedance method.</li>
	<li>Weigh and record the weight of each vial by the electronic balance machine at scheduled time points.</li>
	<li>Analyze collected data in the weighing method and impedance method.19</li>
</ol>

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The authors have nothing to disclose.

The critical step for evaporation measurement in this impedance-based detection is the preparation of the tested solutions. Deionized water cannot be used due to its enormous impedance. Instead, tap water containing conductive ions was used to prepare hyaluronic acid solutions for experiments. However, the electrical properties of tap water were not constant for use. Therefore, normalization, such as the relative evaporation rate to water in this study, was adopted as an alternative index for...

Evaporation is a type of liquid vaporization and occurs along the gas-liquid interface of a collective body of water. The water molecules near the surface become capable of escaping from the liquid due to collision of water molecules. The evaporation rate is an important key factor during the process of evaporation. Generally, a balance or volumetric tube1-3 is widely-used to detect the evaporation of solutions. However, it takes a long time to measure the evaporation rate due to the precision limitation of a balance or a volumetric tube. For this reason, a responsive and high-sensitivity instrument must be developed to probe into the details of the evaporation process.
Electrochemical impedance spectroscopy (EIS) is a fast-response, sensitive and effective experimental means in terms of in-situ impedance detection for electrochemical system characterization4. Therefore, EIS can be applied in various fields, such as recent studies on cellular behavior5, bioanalytical sensing6-7, electrolysis8, conducting polymers9, and electrochemical extraction10. Even though EIS systems had successfully been applied in a wide variety of disciplines, there exist an extremely small number of publications on its application to evaporation research.
Hyaluronic acid, a high molecular weight polysaccharide with strong water-binding potential, is a well-known humectant for cosmetic applications. One hyaluronic acid molecule can bind up to 500 water molecules11 and reach 1,000 times its original volume12. An extremely small amount of hyaluronic acid can possess moisturizing function13-14. Due to the high moisture retention, hyaluronic acid has become an important component of cosmetic humectant products with high commercial value worldwide15.
This study presents the method of a novel impedance-based apparatus featuring high speed detection, small volume sample requirement, and multiple sample measurements16-19. It is presented with a focus on the relative evaporation rate comparison among solutions as a way to validate the superiority of the innovative detection mechanism over a conventional weighing manner.

<table><tbody><tr><td>95% ethanol</td><td>Echo Chemical Co., Ltd., Miaoli, Taiwan</td><td>484000001103C-00EC</td><td></td></tr><tr><td>Acetone</td><td>Avantor Performance Materials Inc., Center Valley, PA, USA</td><td>JTB-9005-68</td><td></td></tr><tr><td>Development solution</td><td>Kemitek Industrial Crop., Hsinchu, Taiwan</td><td>12F01031</td><td>KTD-1</td></tr><tr><td>Etching solution</td><td>eSolv Technology Co., Taipei, Taiwan</td><td></td><td>EG-462</td></tr><tr><td>Hyaluronic acid</td><td>Shandong Freda Biopharm Co., Ltd., Jinan, China</td><td>1010212</td><td>Molecular weight 980k, Cosmetic Grade</td></tr><tr><td>Photoresist solution</td><td>AZ Electronic Materials Taiwan Co., Ltd., Hsinchu, Taiwan</td><td>65101M19</td><td>AZ6112</td></tr><tr><td>8-well silicone array</td><td>Greiner bio-one Inc., Frickenhausen, Baden-W&amp;uuml;rttemberg, Germany</td><td>FlexiPERM</td><td></td></tr><tr><td>ITO glass</td><td>GemTech Optoelectronics Co., Taoyuan, Taiwan</td><td></td><td></td></tr><tr><td>Vial</td><td>Sigma-Aldrich Co. LLC., St. Louis, MO, USA</td><td>854190</td><td></td></tr><tr><td>Film photomask</td><td>Taiwan Mesh Co., Ltd, Taoyuan, Taiwan</td><td></td><td></td></tr><tr><td>Lock-in amplifier</td><td>Stanford Research Systems, Inc., Palo Alto, CA, USA</td><td>SR830</td><td></td></tr><tr><td>Switch relay</td><td>Instrument Technology Research Center, National Applied Research Laboratories, Hsinchu, Taiwan</td><td></td><td></td></tr><tr><td>Electronic balance machine</td><td>Radwag Inc., Radom, Poland</td><td>AS 60/220/C/2</td><td></td></tr></tbody></table>

a high performance impedance-based platform for evaporation rate detection

This paper describes the method of a novel impedance-based platform for the detection of the evaporation rate. The model compound hyaluronic acid was employed here for demonstration purposes. Multiple evaporation tests on the model compound as a humectant with various concentrations in solutions were conducted for comparison purposes. A conventional weight loss approach is known as the most straightforward, but time-consuming, measurement technique for evaporation rate detection. Yet, a clear disadvantage is that a large volume of sample is required and multiple sample tests cannot be conducted at the same time. For the first time in literature, an electrical impedance sensing chip is successfully applied to a real-time evaporation investigation in a time sharing, continuous and automatic manner. Moreover, as little as 0.5 ml of test samples is required in this impedance-based apparatus, and a large impedance variation is demonstrated among various dilute solutions. The proposed high-sensitivity and fast-response impedance sensing system is found to outperform a conventional weight loss approach in terms of evaporation rate detection.

During the evaporation process, the conductive ions in the tested solution became concentrated with the decreasing solution volume, and the impedance of this solution decreased. The rates of weight loss and impedance decrease in the evaporation progress for each tested solution were measured. For comparison purposes, the data in the rates of weight loss and impedance decrease were normalized to water and then plotted together in Figure 5. As illustrated in Figure 5, the weight loss demon...

Watch this Scientific Journal Video about A High Performance Impedance-based Platform for Evaporation Rate Detection at JoVE.com

A High Performance Impedance-based Platform for Evaporation Rate Detection

This paper presents an impedance-based apparatus for evaporation rate detection of solutions. It offers clear advantages over a conventional weight loss approach: a fast response, high-sensitivity detection, a small sample requirement, multiple sample measurements, and easy disassembly for cleaning and reuse purposes.

This paper describes the method of a novel impedance-based platform for the detection of the evaporation rate. The model compound hyaluronic acid was ...

a-high-performance-impedance-based-platform-for-evaporation-rate

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6.5K Views.  Hungkuang University. This paper presents an impedance-based apparatus for evaporation rate detection of solutions. It offers clear advantages over a conventional weight loss approach: a fast response, high-sensitivity detection, a small sample requirement, multiple sample measurements, and easy disassembly for cleaning and reuse purposes.

Video: A High Performance Impedance-based Platform for Evaporation Rate Detection

The Visual Colorimetric Detection of Multi-nucleotide Polymorphisms on a Pneumatic Droplet Manipulation Platform

A simple and visual method to detect multi-nucleotide polymorphism (MNP) was performed on a pneumatic droplet manipulation platform on an open surface. This approach to colorimetric DNA detection was based on the hybridization-mediated growth of gold nanoparticle probes (AuNP probes). The growth size and configuration of the AuNP are dominated by the number of DNA samples hybridized with the probes. Based on the specific size- and shape-dependent optical properties of the nanoparticles, the number of mismatches in a sample DNA fragment to the probes is able to be discriminated. The tests were conducted via droplets containing reagents and DNA samples respectively, and were transported and mixed on the pneumatic platform with the controlled pneumatic suction of the flexible PDMS-based superhydrophobic membrane. Droplets can be delivered simultaneously and precisely on an open-surface on the proposed pneumatic platform that is highly biocompatible with no side effect of DNA samples inside the droplets. Combining the two proposed methods, the multi-nucleotide polymorphism can be detected at sight on the pneumatic droplet manipulation platform; no additional instrument is required. The procedure from installing the droplets on the platform to the final result takes less than 5 min, much less than with existing methods. Moreover, this combined MNP detection approach requires a sample volume of only 10 &#181;l in each operation, which is remarkably less than that of a macro system.

This work presents a simple and visual method to detect multi-nucleotide polymorphisms on a pneumatic droplet manipulation platform. With the proposed method, the entire experiment, including droplet manipulation and detection of multi-nucleotide polymorphisms, can be performed near 23 &#176;C without the aid of advanced instruments.

A simple and visual method to detect multi-nucleotide polymorphism (MNP) was performed on a pneumatic droplet manipulation platform on an open surface. ...

Genetics

Exploring the Effects of Atmospheric Forcings on Evaporation: Experimental Integration of the Atmospheric Boundary Layer and Shallow Subsurface

Evaporation is directly influenced by the interactions between the atmosphere, land surface and soil subsurface. This work aims to experimentally study evaporation under various surface boundary conditions to improve our current understanding and characterization of this multiphase phenomenon as well as to validate numerical heat and mass transfer theories that couple Navier-Stokes flow in the atmosphere and Darcian flow in the porous media. Experimental data were collected using a unique soil tank apparatus interfaced with a small climate controlled wind tunnel. The experimental apparatus was instrumented with a suite of state of the art sensor technologies for the continuous and autonomous collection of soil moisture, soil thermal properties, soil and air temperature, relative humidity, and wind speed. This experimental apparatus can be used to generate data under well controlled boundary conditions, allowing for better control and gathering of accurate data at scales of interest not feasible in the field. Induced airflow at several distinct wind speeds over the soil surface resulted in unique behavior of heat and mass transfer during the different evaporative stages.

A protocol for the design and construction of a soil tank interfaced to a small climate controlled wind tunnel to study the effects of atmospheric forcings on evaporation is presented. Both the soil tank and wind tunnel are instrumented with sensor technologies for the continuous in situ measurement of environmental conditions.

Evaporation is directly influenced by the interactions between the atmosphere, land surface and soil subsurface. This work aims to experimentally study ...

Environment

Fluorescence detection methods for microfluidic droplet platforms

The development of microfluidic platforms for performing chemistry and biology has in large part been driven by a range of potential benefits that accompany system miniaturisation. Advantages include the ability to efficiently process nano- to femoto- liter volumes of sample, facile integration of functional components, an intrinsic predisposition towards large-scale multiplexing, enhanced analytical throughput, improved control and reduced instrumental footprints.1
In recent years much interest has focussed on the development of droplet-based (or segmented flow) microfluidic systems and their potential as platforms in high-throughput experimentation.2-4 Here water-in-oil emulsions are made to spontaneously form in microfluidic channels as a result of capillary instabilities between the two immiscible phases. Importantly, microdroplets of precisely defined volumes and compositions can be generated at frequencies of several kHz. Furthermore, by encapsulating reagents of interest within isolated compartments separated by a continuous immiscible phase, both sample cross-talk and dispersion (diffusion- and Taylor-based) can be eliminated, which leads to minimal cross-contamination and the ability to time analytical processes with great accuracy. Additionally, since there is no contact between the contents of the droplets and the channel walls (which are wetted by the continuous phase) absorption and loss of reagents on the channel walls is prevented.
Once droplets of this kind have been generated and processed, it is necessary to extract the required analytical information. In this respect the detection method of choice should be rapid, provide high-sensitivity and low limits of detection, be applicable to a range of molecular species, be non-destructive and be able to be integrated with microfluidic devices in a facile manner. To address this need we have developed a suite of experimental tools and protocols that enable the extraction of large amounts of photophysical information from small-volume environments, and are applicable to the analysis of a wide range of physical, chemical and biological parameters. Herein two examples of these methods are presented and applied to the detection of single cells and the mapping of mixing processes inside picoliter-volume droplets. We report the entire experimental process including microfluidic chip fabrication, the optical setup and the process of droplet generation and detection.

Droplet-based microfluidic platforms are promising candidates for high throughput experimentation since they are able to generate picoliter, self-compartmentalized vessels inexpensively at kHz rates. Through integration with fast, sensitive and high resolution fluorescence spectroscopic methods, the large amounts of information generated within these systems can be efficiently extracted, harnessed and utilized.

The development of microfluidic platforms for performing chemistry and biology has in large part been driven by a range of potential benefits that ...

Bioengineering

Taking Advantage of Reduced Droplet-surface Interaction to Optimize Transport of Bioanalytes in Digital Microfluidics

Digital microfluidics (DMF), a technique for manipulation of droplets, is a promising alternative for the development of &#8220;lab-on-a-chip&#8221; platforms. Often, droplet motion relies on the wetting of a surface, directly associated with the application of an electric field; surface interactions, however, make motion dependent on droplet contents, limiting the breadth of applications of the technique.
Some alternatives have been presented to minimize this dependence. However, they rely on the addition of extra chemical species to the droplet or its surroundings, which could potentially interact with droplet moieties. Addressing this challenge, our group recently developed Field-DW devices to allow the transport of cells and proteins in DMF, without extra additives.
Here, the protocol for device fabrication and operation is provided, including the electronic interface for motion control. We also continue the studies with the devices, showing that multicellular, relatively large, model organisms can also be transported, arguably unaffected by the electric fields required for device operation.

The protocol for fabrication and operation of field dewetting devices (Field-DW) is described, as well as the preliminary studies of the effects of electric fields on droplet contents.

Digital microfluidics (DMF), a technique for manipulation of droplets, is a promising alternative for the development of &#8220;lab-on-a-chip&#8221; ...

Quantification and Size-profiling of Extracellular Vesicles Using Tunable Resistive Pulse Sensing

Extracellular vesicles (EVs), including &#8216;microvesicles&#8217; and &#8216;exosomes&#8217;, are highly abundant in bodily fluids. Recent years have witnessed a tremendous increase in interest in EVs. EVs have been shown to play important roles in various physiological and pathological processes, including coagulation, immune responses, and cancer. In addition, EVs have potential as therapeutic agents, for instance as drug delivery vehicles or as regenerative medicine. Because of their small size (50 to 1,000 nm) accurate quantification and size profiling of EVs is technically challenging.
This protocol describes how tunable resistive pulse sensing (tRPS) technology, using the qNano system, can be used to determine the concentration and size of EVs. The method, which relies on the detection of EVs upon their transfer through a nano sized pore, is relatively fast, suffices the use of small sample volumes and does not require the purification and concentration of EVs. Next to the regular operation protocol an alternative approach is described using samples spiked with polystyrene beads of known size and concentration. This real-time calibration technique can be used to overcome technical hurdles encountered when measuring EVs directly in biological fluids.

Extracellular vesicles play important roles in physiological and pathological processes, including coagulation, immune responses, and cancer or as potential therapeutic agents in drug delivery or regenerative medicine. This protocol presents methods for the quantification and size characterization of isolated and non-isolated extracellular vesicles in various fluids using tunable resistive pulse sensing.

Extracellular vesicles (EVs), including &#8216;microvesicles&#8217; and &#8216;exosomes&#8217;, are highly abundant in bodily fluids. Recent years have ...

A Microfluidic-based Electrochemical Biochip for Label-free DNA Hybridization Analysis

Miniaturization of analytical benchtop procedures into the micro-scale provides significant advantages in regards to reaction time, cost, and integration of pre-processing steps. Utilizing these devices towards the analysis of DNA hybridization events is important because it offers a technology for real time assessment of biomarkers at the point-of-care for various diseases. However, when the device footprint decreases the dominance of various physical phenomena increases. These phenomena influence the fabrication precision and operation reliability of the device. Therefore, there is a great need to accurately fabricate and operate these devices in a reproducible manner in order to improve the overall performance. Here, we describe the protocols and the methods used for the fabrication and the operation of a microfluidic-based electrochemical biochip for accurate analysis of DNA hybridization events. The biochip is composed of two parts: a microfluidic chip with three parallel micro-channels made of polydimethylsiloxane (PDMS), and a 3 x 3 arrayed electrochemical micro-chip. The DNA hybridization events are detected using electrochemical impedance spectroscopy (EIS) analysis. The EIS analysis enables monitoring variations of the properties of the electrochemical system that are dominant at these length scales. With the ability to monitor changes of both charge transfer and diffusional resistance with the biosensor, we demonstrate the selectivity to complementary ssDNA targets, a calculated detection limit of 3.8 nM, and a 13% cross-reactivity with other non-complementary ssDNA following 20 min&#160;of incubation. This methodology can improve the performance of miniaturized devices by elucidating on the behavior of diffusion at the micro-scale regime and by enabling the study of DNA hybridization events.

We present a microfluidic-based electrochemical biochip for DNA hybridization detection. Following ssDNA probe functionalization, the specificity, sensitivity, and detection limit are studied with complementary and non-complementary ssDNA targets. Results illustrate the influence of the DNA hybridization events on the electrochemical system, with a detection limit of 3.8 nM.

Miniaturization of analytical benchtop procedures into the micro-scale provides significant advantages in regards to reaction time, cost, and integration ...

Aqueous Droplets Used as Enzymatic Microreactors and Their Electromagnetic Actuation

For the successful implementation of microfluidic reaction systems, such as PCR and electrophoresis, the movement of small liquid volumes is essential. In conventional lab-on-a-chip-platforms, solvents and samples are passed through defined microfluidic channels with complex flow control installations. The droplet actuation platform presented here is a promising alternative. With it, it is possible to move a liquid drop (microreactor) on a planar surface of a reaction platform (lab-in-a-drop). The actuation of microreactors on the hydrophobic surface of the platform is based on the use of magnetic forces acting on the outer shell of the liquid drops which is made of a thin layer of superhydrophobic magnetite particles. The hydrophobic surface of the platform is needed to avoid any contact between the liquid core and the surface to allow a smooth movement of the microreactor. On the platform, one or more microreactors with volumes of 10 &#181;L can be positioned and moved simultaneously. The platform itself consists of a 3 x 3 matrix of electrical double coils which accommodate either neodymium or iron cores. The magnetic field gradients are automatically controlled. By variation of the magnetic field gradients, the microreactors' magnetic hydrophobic shell can be manipulated automatically to move the microreactor or open the shell reversibly. Reactions of substrates and corresponding enzymes can be initiated by merging the microreactors or bringing them into contact with surface immobilized catalysts.

Lab-in-a-drop reaction systems allow the versatile implementation of complex reactions in a microfluidic scale. An automated actuation platform consisting of a 3 x 3 matrix of electromagnetic coils was developed and successfully used to merge two 10 &#181;L microreactors and thereby initiate an enzymatic reaction in the resulting liquid marbles.

For the successful implementation of microfluidic reaction systems, such as PCR and electrophoresis, the movement of small liquid volumes is essential. In ...

Additive Manufacturing-Enabled Low-Cost Particle Detector

As particles with a size of 1 &#181;m or smaller pose a severe health risk to the human body, the detection and regulation of particle emissions are of great importance. A large share of particulate emissions are emitted by the transport sector. Most of the commercially available particle detectors are bulky, very expensive, and need additional equipment. This paper presents a protocol to build and test a standalone particle detector that is small and cost-efficient. 
The focus of this paper lies in the description of the detailed construction manual with video and the sensor evaluation procedure. The computer-aided design model of the sensor is included in the supplemental material. The manual explains all the construction steps, from 3D printing to the fully operational sensor. The sensor can detect charged particles and is therefore suitable for a wide range of applications. A possible field of application would be soot detection from power plants, wildfires, industries, and automobiles.

Here, we present a protocol on how to build and test a simple but efficient low-cost particle detector.

As particles with a size of 1 &#181;m or smaller pose a severe health risk to the human body, the detection and regulation of particle emissions are of ...

A Performance-testing Platform for a Conduction Micropump with an FR-4 Copper-clad Electrode Plate

Here, a conduction micropump with symmetric planar electrode pairs prepared on flame-retardant glass-reinforced epoxy (FR-4) copper-clad laminate (CCL) is fabricated. It is used to investigate the influence of chamber dimensions on the performance of a conduction micropump and to determine the reliability of the conduction pump when acetone is used as the working fluid. A testing platform is set up to evaluate conduction micropump performance under different conditions. When the chamber height is 0.2 mm, the pump pressure reaches its peak value.

This paper presents a protocol for the fabrication of a conduction micropump using symmetric planar electrodes on flame-retardant glass-reinforced epoxy (FR-4) copper-clad laminate (CCL) to test the influence of chamber dimensions on the performance of a conduction micropump.

Here, a conduction micropump with symmetric planar electrode pairs prepared on flame-retardant glass-reinforced epoxy (FR-4) copper-clad laminate (CCL) is ...

Dry Film Photoresist-based Electrochemical Microfluidic Biosensor Platform: Device Fabrication, On-chip Assay Preparation, and System Operation

In recent years, biomarker diagnostics became an indispensable tool for the diagnosis of human disease, especially for the point-of-care diagnostics. An easy-to-use and low-cost sensor platform is highly desired to measure various types of analytes (e.g., biomarkers, hormones, and drugs) quantitatively and specifically. For this reason, dry film photoresist technology - enabling cheap, facile, and high-throughput fabrication - was used to manufacture the microfluidic biosensor presented here. Depending on the bioassay used afterwards, the versatile platform is capable of detecting various types of biomolecules. For the fabrication of the device, platinum electrodes are structured on a flexible polyimide (PI) foil in the only clean-room process step. The PI foil serves as a substrate for the electrodes, which are insulated with an epoxy-based photoresist. The microfluidic channel is subsequently generated by the development and lamination of dry film photoresist (DFR) foils onto the PI wafer. By using a hydrophobic stopping barrier in the channel, the channel is separated into two specific areas: an immobilization section for the enzyme-linked assay and an electrochemical measurement cell for the amperometric signal readout.
The on-chip bioassay immobilization is performed by the adsorption of the biomolecules to the channel surface. The glucose oxidase enzyme is used as a transducer for electrochemical signal generation. In the presence of the substrate, glucose, hydrogen peroxide is produced, which is detected at the platinum working electrode. The stop-flow technique is applied to obtain signal amplification along with rapid detection. Different biomolecules can quantitatively be measured by means of the introduced microfluidic system, giving an indication of different types of diseases, or, in regard to therapeutic drug monitoring, facilitating a personalized therapy.

A microfluidic biosensor platform was designed and fabricated using low-cost dry film photoresist technology for the rapid and sensitive quantification of various analytes. This single-use system allows for the electrochemical readout of on-chip-immobilized enzyme-linked assays by means of the stop-flow technique.

In recent years, biomarker diagnostics became an indispensable tool for the diagnosis of human disease, especially for the point-of-care diagnostics. An ...