Rapid Micromolding of Sub-100 µm Microfluidic Channels Using an 8K Stereolithographic Resin 3D Printer.

Engineering microfluidic devices relies on the ability to manufacture sub-100 micrometer fluidic channels. Conventional lithographic methods provide high resolution but require costly exposure tools and outsourcing of masks, which extends the turnaround time to several days. The desire to accelerate design/test cycles has motivated the rapid prototyping of microfluidic channels; however, many of these methods (e.

Digital Assays Part II: Digital Protein and Cell Assays.

A digital assay is one in which the sample is partitioned into many containers such that each partition contains a discrete number of biological entities (0, 1, 2, 3, . . .

Digital Assays Part I: Partitioning Statistics and Digital PCR.

A digital assay is one in which the sample is partitioned into many small containers such that each partition contains a discrete number of biological entities (0, 1, 2, 3, …). A powerful technique in the biologist's toolkit, digital assays bring a new level of precision in quantifying nucleic acids, measuring proteins and their enzymatic activity, and probing single-cell genotypes and phenotypes. Part I of this review begins with the benefits and Poisson statistics of partitioning, including sources of error.

Programming microbes using pulse width modulation of optical signals.

Cells transmit and receive information via signalling pathways. A number of studies have revealed that information is encoded in the temporal dynamics of these pathways and has highlighted how pathway architecture can influence the propagation of signals in time and space. The functional properties of pathway architecture can also be exploited by synthetic biologists to enable precise control of cellular physiology.

Droplet morphometry and velocimetry (DMV): a video processing software for time-resolved, label-free tracking of droplet parameters.

Emerging assays in droplet microfluidics require the measurement of parameters such as drop size, velocity, trajectory, shape deformation, fluorescence intensity, and others. While micro particle image velocimetry (μPIV) and related techniques are suitable for measuring flow using tracer particles, no tool exists for tracking droplets at the granularity of a single entity. This paper presents droplet morphometry and velocimetry (DMV), a digital video processing software for time-resolved droplet analysis.

Plug-and-play, single-chip photoplethysmography.

Remote patient monitoring (RPM) relies on low-cost, low-power, wearable sensors for continuous physiological assessment. Photoplethysmographic (PPG) sensors generally require >10 components, occupy an area >300 mm(2), consume >10 mW power, and cost >$20 USD. Although the principle of PPG sensing is straightforward, in practice, a robust implementation requires a careful design including optical alignment, analog circuits, ambient light cancellation, and power management.

Optical microplates for high-throughput screening of photosynthesis in lipid-producing algae.

It is well known that biological systems respond to chemical signals as well as physical stimuli. The workhorses of high throughput screening, microplates and pipetting robots, are well suited for screening chemical stimuli; however, there are fewer options for screening physical stimuli, particularly those which involve temporal patterns. This paper presents an optical microplate for photonic high-throughput screening.

Field-free particle focusing in microfluidic plugs.

Particle concentration is a key unit operation in biochemical assays. Although there are many techniques for particle concentration in continuous-phase microfluidics, relatively few are available in multiphase (plug-based) microfluidics. Existing approaches generally require external electric or magnetic fields together with charged or magnetized particles.

Capillary fractionation of HPLC substrates by a microfluidic droplet generator for high throughput analysis.

Biochemical samples are complex mixtures containing 1000's of components which often must be fractionated prior to analysis. Conventional fraction collectors, which can only accommodate 10's of fractions, are not well suited for high throughput analysis. This paper describes microfractionation in droplets (μFD), a scalable microfluidic technique for generating thousands of fractions.

Shape dependent Laplace vortices in deformed liquid-liquid slug flow.

Understanding the hydrodynamics of liquid-liquid slug flow is important in the emerging field of plug-based microfluidics; however, the subtle aspects of the vortex geometry are still not comprehensively understood. This paper discusses the hydrodynamics of deformation dependent vortices that develop inside a water-in-oil slug as it flows through a channel. In contrast to prior studies, our simulations and experiments on slug flow reveal multiple vortices inside the moving slug, caused by the deformation of the hemispherical caps by Laplace pressures.

Optical microplates for photonic high throughput screening of algal photosynthesis and biofuel production.

Biological systems respond not only to chemical stimuli (drugs, proteins) but also to physical stimuli (light, heat, stress). Though there are many high throughput tools for screening chemical stimuli, no such tool exists for screening of physical stimuli. This paper presents a novel instrument for photonic high throughput screening of photosynthesis, a light-driven bioprocess.

High speed low noise multiplexed three color absorbance photometry.

Multispectral photometry is often required to distinguish samples in flow injection analysis and flow cytometry; however, the cost of multiple light detectors, filters, and optical paths contribute to the high cost of multicolor and spectral detection systems. This paper describes frequency division multiplexing (FDM), a simple approach for performing multi-wavelength absorbance photometry with a single light detector and a single interrogation window. In previous efforts, modulation frequencies were <10 KHz, resulting in a detector bandwidth of <20 Hz.

A modular approach for the generation, storage, mixing, and detection of droplet libraries for high throughput screening.

The desire to make microfluidic technology more accessible to the biological research community has led to the notion of "modular microfluidics", where users can build a fluidic system using a toolkit of building blocks. This paper applies a modular approach for performing droplet-based screening, including the four integral steps of library generation, storage, mixing, and optical interrogation. Commercially available cross-junctions are used for drop generation, flexible capillary tubing for storage, and tee-junctions for serial mixing.

Microfluidic encapsulation of cells in alginate capsules for high throughput screening.

Microdroplet systems can drastically reduce costs and increase throughput in high throughput screening (HTS) assays. While droplets are well suited for biomolecular screening, cell-based screens are more problematic because eukaryotes typically require attachment to solid supports to maintain viability and function. This paper describes an economical, off-the-shelf microfluidic system which encapsulates eukaryotic cells in gelatinous alginate capsules for the purpose of HTS.