This Account summarizes techniques for fabrication and applications in biomedicine of microfluidic devices fabricated in poly(dimethylsiloxane) (PDMS). The methods and applications described focus on the exploitation of the physical and chemical properties of PDMS in the fabrication or actuation of the devices. Fabrication of channels in PDMS is simple, and it can be used to incorporate other materials and structures through encapsulation or sealing (both reversible and irreversible).

Poly(dimethylsiloxane) as a material for fabricating microfluidic devices.

■ Abstract Fluid flow at the microscale exhibits unique phenomena that can be leveraged to fabricate devices and components capable of performing functions useful for biological studies. The physics of importance to microfluidics are reviewed. Common methods of fabricating microfluidic devices and systems are described. Components, including valves, mixers, and pumps, capable of controlling fluid flow by utilizing the physics of the microscale are presented. Techniques for sensing flow characteristics are described and examples of devices and systems that perform bioanalysis are presented. The focus of this review is microscale phenomena and the use of the physics of the scale to create devices and systems that provide functionality useful to the life sciences.

https://www.researchgate.net/profile/Glennys_Mensing/publication/11260597_Physics_and_applications_of_microfluidics_in_biology/links/5437f5160cf2027cbb206767.pdf

Physics and applications of microfluidics in biology.

Miniaturization can expand the capability of existing bioassays, separation technologies and chemical synthesis techniques. Although a reduction in size to the micrometre scale will usually not change the nature of molecular reactions, laws of scale for surface per volume, molecular diffusion and heat transport enable dramatic increases in throughput. Besides the many microwell-plate- or bead-based methods, microfluidic chips have been widely used to provide small volumes and fluid connections and could eventually outperform conventionally used robotic fluid handling. Moreover, completely novel applications without a macroscopic equivalent have recently been developed. This article reviews current and future applications of microfluidics and highlights the potential of 'lab-on-a-chip' technology for drug discovery.

Lab-on-a-chip: microfluidics in drug discovery.

Micromachining technology was used to prepare chemical analysis systems on glass chips (1 centimeter by 2 centimeters or larger) that utilize electroosmotic pumping to drive fluid flow and electrophoretic separation to distinguish sample components. Capillaries 1 to 10 centimeters long etched in the glass (cross section, 10 micrometers by 30 micrometers) allow for capillary electrophoresis-based separations of amino acids with up to 75,000 theoretical plates in about 15 seconds, and separations of about 600 plates can be effected within 4 seconds. Sample treatment steps within a manifold of intersecting capillaries were demonstrated for a simple sample dilution process. Manipulation of the applied voltages controlled the directions of fluid flow within the manifold. The principles demonstrated in this study can be used to develop a miniaturized system for sample handling and separation with no moving parts.

Micromachining a miniaturized capillary electrophoresis-based chemical analysis system on a chip

Droplet microfluidics generates and manipulates discrete droplets through immiscible multiphase flows inside microchannels Due to its remarkable advantages, droplet microfluidics bears significant value in an extremely wide range of area In this review, we provide a comprehensive and in-depth insight into droplet microfluidics, covering fundamental research from microfluidic chip fabrication and droplet generation to the applications of droplets in bio(chemical) analysis and materials generation The purpose of this review is to convey the fundamentals of droplet microfluidics, a critical analysis on its current status and challenges, and opinions on its future development We believe this review will promote communications among biology, chemistry, physics, and materials science

Emerging Droplet Microfluidics

The device has a pressing device (5) for securing an optimal contact of a platform and heating and cooling units (3). The platform has a lower part or a base plate with structures (4), which includes open structures (1) that are closed by a thin cover (2). The cover is in direct contact to the heating and cooling units. Different temperature zones are mechanically and thermally separated and lie on sides of the platform. A gap between tempering units of the device is used for detection of a valve and a pump. An integrated holder is provided for the platform that is utilized in a holding frame.

Operating device for e.g. tempering fluid platforms, has pressing device for securing optimal contact of platform and heating and cooling units, where platform has lower part or base plate with structures, which includes open structures

In the hospital Intensive Care Units (ICU) there is an even greater demand by the physicians for the continuous immunosuppressant drug monitoring in the transplanted patient therapy, in order to avoid different risks and diseases which may occur as result of some drug dosage related effect, such the rejection crisis or sepsis. Here we present a novel design of a point of care testing (POCT) device for the drug dose—adjustment in this kind of patients. The working principle of the device will be discussed. Preliminary tests on the immunoassay strategies for immunosuppressant drugs recognition such as on the optical chip realization and characterization are reported.

A Point-of-Care Device for Immunosuppressants Monitoring in Transplanted Patients

Lab-on-a-chip systems are innovative tools for the detection and identification of microbial pathogens in human and
veterinary medicine. The major advantages are small sample volume and a compact design. Several fluidic modules have
been developed to transform analytical procedures into miniaturized scale including sampling, sample preparation, target
enrichment, and detection procedures.
We present evaluation data for single modules that will be integrated in a chip system for the detection of pathogens.
A microfluidic chip for purification of nucleic acids was established for cell lysis using magnetic beads. This assay was
evaluated with spiked environmental aerosol and swab samples. Bacillus thuringiensis was used as simulant for Bacillus
anthracis, which is closely related but non-pathogenic for humans. Stationary PCR and a flow-through PCR chip module
were investigated for specific detection of six highly pathogenic bacteria. The conventional PCR assays could be
transferred into miniaturized scale using the same temperature/time profile.
We could demonstrate that the microfluidic chip modules are suitable for the respective purposes and are promising tools
for the detection of bacterial pathogens. Future developments will focus on the integration of these separate modules to
an entire lab-on-a-chip system.

Lab-on-a-chip modules for detection of highly pathogenic bacteria: from sample preparation to detection

Integrated lab-on-a-chip

The growing complexity of microfluidic devices is currently leading to an increased dimensional scale dynamics, i.e. the
range of sizes of features on the microfluidic device is steadily increasing, from centimeter-sized features like reservoirs
over millimeter-sized features like fluidic connections and micrometer-sized features like microchannels to nanometersized
features like surface textures. In order manufacture these devices with polymer replication technologies like
injection molding and hot embossing, molding tools (masters) have to be fabricated which contain the same structural
dynamic range. Often, this is not possible using a single tooling technology. We therefore present examples of such tools
which have been fabricated using two techniques on the same master structure, namely precision mechanical machining,
single-point diamond turning (SPDT) and stereolithography.

Claudia Gärtner

Papers

Operating device for e.g. tempering fluid platforms, has pressing device for securing optimal contact of platform and heating and cooling units, where platform has lower part or base plate with structures, which includes open structures

A Point-of-Care Device for Immunosuppressants Monitoring in Transplanted Patients

Lab-on-a-chip modules for detection of highly pathogenic bacteria: from sample preparation to detection

Integrated lab-on-a-chip

Hybrid tooling technologies for injection molded and hot embossed polymeric microfluidic devices