Same Day Microfluidics: From Design to Device in Under Three Hours

Integrated elastomeric valves, also referred to as Quake valves, enable precise control and manipulation of fluid within microfluidic devices. Fabrication of such valves requires bonding of multiple layers of the silicone polymer polydimethylsiloxane (PDMS). The conventional method for PDMS–PDMS bonding is to use varied ratios of base to crosslinking agent between layers, typically 20:1 and 5:1. This bonding technique, known as ‘off-ratio bonding’, provides strong, effective PDMS–PDMS bonding for multi-layer soft-lithography, but it can yield adverse PDMS material properties and can be wasteful of PDMS. Here we demonstrate the effectiveness of ‘on-ratio’ PDMS bonding, in which both layers use a 10:1 base-to-crosslinker ratio, for multilayer soft lithography. We show the efficacy of this technique among common variants of PDMS: Sylgard 184, RTV 615, and Sylgard 182.

Microfluidics is a prominent field used to analyze small amounts of biological fluids. Co-Flow microfluidic devices can be used to study red blood cell aggregation in blood samples under a controlled shear rate. The purpose of this paper is to optimize the parameters of a co-flow device in order to produce a linear velocity profile in blood samples which would provide a constant shear rate. This is desired as the eventual goal is to use an ultrasonic measurement sensor with the co-flow microfluidic device to analyze red blood cell aggregates. Computational fluid dynamic simulations were performed to model a microfluidic device. The simulation results were verified by μPIV of the experimental microfluidic device. Modifications were made to the geometry and flow rate ratio of the microfluidic device to produce a more linear velocity profile. By using a flow rate ratio of 50:1 of shearing fluid to sheared fluid, we were able to achieve a velocity profile in the blood layer that is approximately linear.

The polymer polydimethylsiloxane (PDMS) is widely used to build microfluidic devices compatible with cell culture. Whilst convenient in manufacture, PDMS has the disadvantage that it can absorb small molecules such as drugs. In microfluidic devices like “Organs-on-Chip”, designed to examine cell behavior and test the effects of drugs, this might impact drug bioavailability. Here we developed an assay to compare the absorption of a test set of four cardiac drugs by PDMS based on measuring the residual non-absorbed compound by High Pressure Liquid Chromatography (HPLC). We showed that absorption was variable and time dependent and not determined exclusively by hydrophobicity as claimed previously. We demonstrated that two commercially available lipophilic coatings and the presence of cells affected absorption. The use of lipophilic coatings may be useful in preventing small molecule absorption by PDMS.

High-throughput fabrication of graphically encoded hydrogel microparticles is achieved by combining flow contact lithography in a multichannel microfluidic device and a high capacity 25 mm LED UV source. Production rates of chemically homogeneous particles are improved by two orders of magnitude. Additionally, the custom-built contact lithography instrument provides an affordable solution for patterning complex microstructures on surfaces.

Paper-based microfluidics: What can we expect?

Recent calls for reform in undergraduate biology education have emphasized integrating research experiences into the learning experiences of all undergraduates. Contemporary science research increasingly demands collaboration across disciplines and institutions to investigate complex research questions, providing new contexts and models for involving undergraduates in research. In this study, we examined the experiences of undergraduates participating in a multi-institution and interdisciplinary biology research network. Unlike the traditional apprenticeship model of research, in which a student participates in research under the guidance of a single faculty member, students participating in networked research have the opportunity to develop relationships with additional faculty and students working in other areas of the project, at their own and at other institutions. We examined how students in this network develop social ties and to what extent a networked research experience affords opportunities for students to develop social, cultural, and human capital. Most studies of undergraduate involvement in science research have focused on documenting student outcomes rather than elucidating how students gain access to research experiences or how elements of research participation lead to desired student outcomes. By taking a qualitative approach framed by capital theories, we have identified ways that undergraduates utilize and further develop various forms of capital important for success in science research. In our study of the first 16 months of a biology research network, we found that undergraduates drew upon a combination of human, cultural, and social capital to gain access to the network. Within their immediate research groups, students built multidimensional social ties with faculty, peers, and others, yielding social capital that can be drawn upon for information, resources, and support. They reported developing cultural capital in the form of learning to think and work like a scientist—a scientific habitus. They reported developing human capital in the forms of technical, analytical, and communication skills in scientific research. Most of the students had little, direct interaction with network members in other research groups and thus developed little cross-institutional capital. The exception to this trend was at one institution that housed three research groups. Because proximity facilitated shared activities, students across research groups at this institution developed cross-lab ties with faculty and peers through which they developed social, cultural, and human capital. An important long-term concern is whether the capital students have developed will help them access opportunities in science beyond the network. At this point, many undergraduates have had limited opportunities to actually draw on capital beyond the network. Nevertheless, a number of students demonstrated awareness that they had developed resources that they could use in other scientific contexts.

Research can be defined as a study on a particular topic in detail in a systematic and scientific method. The purposes of research are to find something new, to prove or support a theory, to contribute knowledge in a field, or to increase awareness about something. Medical research includes basic research to clinical research which leads to advancement in the pharmaceutical industry, to improve healthcare and public health. Research among undergraduate students will expand knowledge in their field, increases interest in their career and improves their resume for job search. A cross-sectional survey was conducted among undergraduate dental students to evaluate the awareness of the importance of research. The study population in the study are the undergraduate dental students with a sample size of 100. The questionnaire consisted of 20 questions and was shared to undergraduate dental students using online survey platform. 80% of the participants college encourage students to do research, 11% of the students college does not and 9% of the students college partially encourages the students to do research. 48% of the participants said they would continue doing research, 17% said they would not continue doing research and 35% said they might continue doing research. From the results obtained, we can conclude that moderate to a good level of awareness is seen in undergraduate dental students. More awareness should be created and undergraduate students should be encouraged to do research and make the best use of their college years.

Undergraduate students rarely have an opportunity to learn about, and have hands-on experience with, stable-isotope geochemistry even though this subdiscipline of geoscience is widely used in numerous fields, including petrology, geochemistry, hydrogeology, environmental geology, and paleoclimatology. A common misperception is that the equipment needed to make stable-isotope extractions is expensive, difficult to operate and maintain, and inaccessible to undergraduate students. In fact, it is possible to make stable-isotope extractions with minimal training on equipment that is easily assembled, relatively inexpensive (costing between eight and twelve thousand dollars, excluding a mass spectrometer), and easy to maintain. Here we provide a list of parts, equipment, and instructions needed to build a vacuum extraction line that can be used for the analysis of hydrogen, carbon, and oxygen isotopes from carbonates and water. We have incorporated stable-isotope laboratory exercises into four undergraduate courses. These exercises have helped prepare our students for graduate study and industrial work in the geosciences and environmental sciences and have created new opportunities for them to do research.

We present a simple, fast, and inexpensive new printing-based fabrication process for flexible and wearable microfluidic channels and devices. Microfluidic devices are fabricated on textiles (fabric) for applications in clothing-based wearable microfluidic sensors and systems. The wearable and flexible microfluidic devices are comprised of water-insoluable screen-printable plastisol polymer. Sheets of paper are used as sacrificial substrates for multiple layers of polymer on the fabric’s surface. Microfluidic devices can be made within a short time using simple processes and inexpensive equipment that includes a laser cutter and a thermal laminator. The fabrication process is characterized to demonstrate control of microfluidic channel thickness and width. Film thickness smaller than 100 micrometers and lateral dimensions smaller than 150 micrometers are demonstrated. A flexible microfluidic mixer is also developed on fabric and successfully tested on both flat and curved surfaces at volumetric flow rates ranging from 5.5–46 ml min−1.

Recently published studies have shown that microfluidic devices fabricated by in-house three-dimensional (3D) printing, computer numerical control (CNC) milling and laser engraving have a good quality of performance. The 3-in-1 3D printers, desktop machines that integrate the three primary functions in a single user-friendly set-up are now available for computer-controlled adaptable surface processing, for less than USD 1000. Here, we demonstrate that 3-in-1 3D printer-based micromachining is an effective strategy for creating microfluidic devices and an easier and more economical alternative to, for instance, conventional photolithography. Our aim was to produce plastic microfluidic chips with engraved microchannel structures or micro-structured plastic molds for casting polydimethylsiloxane (PDMS) chips with microchannel imprints. The reproducability and accuracy of fabrication of microfluidic chips with straight, crossed line and Y-shaped microchannel designs were assessed and their microfluidic performance checked by liquid stream tests. All three fabrication methods of the 3-in-1 3D printer produced functional microchannel devices with adequate solution flow. Accordingly, 3-in-1 3D printers are recommended as cheap, accessible and user-friendly tools that can be operated with minimal training and little starting knowledge to successfully fabricate basic microfluidic devices that are suitable for educational work or rapid prototyping.

Computation technology has dramatically changed the world around us; you can hardly find an area where cell phones have not saturated the market, yet there is a significant lack of breakthroughs in the development to integrate the computer with biological environments. This is largely the result of the incompatibility of the materials used in both environments; biological environments and experiments tend to need aqueous environments. To help aid in these development chemists, engineers, physicists and biologists have begun to develop microfluidics to help bridge this divide. Unfortunately, the microfluidic devices required large external support equipment to run the device. This thesis presents a series of several microfluidic methods that can help integrate engineering and biology by exploiting nanotechnology to help push the field of microfluidics back to its intended purpose, small integrated biological and electrical devices. I demonstrate this goal by developing different methods and devices to (1) separate membrane bound proteins with the use of microfluidics, (2) use optical technology to make fiber optic cables into protein sensors, (3) generate new fluidic devices using semiconductor material to manipulate single cells, and (4) develop a new genetic microfluidic based diagnostic assay that works with current PCR methodology to provide faster and cheaper results. All of these methods and systems can be used as components to build a self-contained biomedical device.

A review of the recent achievements and future trends on 3D printed microfluidic devices for bioanalytical applications

The scientific and technological underpinnings of microfluidic paper-based analytical devices (μPADs), a field initiated by Whitesides' research group in 2007, pertain to the design and fabrication of analytical devices composed of paper or other porous membranes that manipulate minute fluid volumes (10-6 to 10-9 L) through the principle of capillary action. While the employment of paper in the fabrication of microfluidic devices for analytical purposes confers numerous advantages, it is imperative to acknowledge the challenges that must be surmounted to ensure the reliability and dependability of the industry in the realm of point-of-care testing (POCT). This review delineates the evolution of paper in analytical chemistry, from early chromatographic separations to modern μPADs, followed by an exhaustive examination of the challenges currently confronting researchers who utilize μPADs as analytical instruments. The methods to surmount these challenges will be expounded by presenting numerous real-world applications, predominantly in the health sciences domain.

We developed a novel blood testing device which extracts plasma from a minute amount of whole blood and detects specific proteins in the plasma using LSPR (localized surface plasmon resonance). We detected an antigen-antibody reaction by measuring light scattering by gold nanoparticles in the device, and demonstrated that the present device permits detection of tPA (tissue plasminogen activator). I. INTRODUCTION The concern for healthcare and preventive medical care is rising with increase of the lifestyle-related diseases and population aging. There is going to be a greater demand for periodical and on-site diagnosable blood tests which are carried out at home by nonprofessional people. Then, many research groups have already reported about microfluidic devices to separate blood for simple blood testing. For example, the microfluidic devices which extract blood plasma using the Zweifach-Fung effect were developed(1). However, these devices require flow control using a pump. Also, the microfluidic device which separates blood into cells and plasma by dielectrophoresis was developed(2). However, this device causes hemolysis and blood deterioration due to joule heat. Therefore, we developed a microfluidic device for plasma extraction using capillary force without external driving sources. Moreover, we developed a novel technique for LSPR-based non-labeling detection of biomolecules in the device.

Flexible manipulation of microfluids using optically regulated adsorption/desorption of hydrophobic materials