Routing of Fluidic Circuits Using Skeletons of Polygonal Figures and Compound Splines

Routing of channels between elementary fluidic elements is an important stage in the design of new fluidic devices. This paper considers usage skeletons of polygonal figures and compound splines in routing of fluidic circuits.

Lumped-Parameter Response Time Models for Pneumatic Circuit Dynamics

Resistor–capacitor (RC) response time models for pressurizing and depressurizing a pneumatic capacitor (mass accumulator) through a resistor (flow restriction) comprise a framework to systematically analyze complex fluidic circuits. A model for pneumatic resistance is derived from a combination of fundamental fluid mechanics and experimental results. Models describing compressible fluid capacitance are derived from thermodynamic first principles and validated experimentally. The models are combined to derive the ordinary differential equations that describe the RC dynamics. These equations are solved analytically for rigid capacitors and numerically for deformable capacitors to generate pressure response curves as a function of time. The dynamic pressurization and depressurization response times to reach 63.2% (or 1−e−1) of exponential decay are validated in simple pneumatic circuits with combinations of flow restrictions ranging from 100 μm to 1 mm in diameter, source pressures ranging from 5 to 200 kPa, and capacitor volumes of 0.5 to 16 mL. Our RC models predict the response times, which range from a few milliseconds to multiple seconds depending on the combination, with a coefficient of determination of r2=0.983. The utility of the models is demonstrated in a multicomponent fluidic circuit to find the optimal diameter of tubing between a three-way electromechanical valve and a pneumatic capacitor to minimize the response time for the changing pressure in the capacitor. These lumped-parameter models represent foundational blocks upon which timing models of pneumatic circuits can be built for a variety of applications from soft robotics and industrial automation to high-speed microfluidics.

Microfluidic Quantitative PCR Detection of 12 Transgenes from Horse Plasma for Gene Doping Control

Gene doping, an activity which abuses and misuses gene therapy, is a major concern in sports and horseracing industries. Effective methods capable of detecting and monitoring gene doping are urgently needed. Although several PCR-based methods that detect transgenes have been developed, many of them focus only on a single transgene. However, numerous genes associated with athletic ability may be potential gene-doping material. Here, we developed a detection method that targets multiple transgenes. We targeted 12 genes that may be associated with athletic performance and designed two TaqMan probe/primer sets for each one. A panel of 24 assays was prepared and detected via a microfluidic quantitative PCR (MFQPCR) system using integrated fluidic circuits (IFCs). The limit of detection of the panel was 6.25 copy/μL. Amplification-specificity was validated using several concentrations of reference materials and animal genomic DNA, leading to specific detection. In addition, target-specific detection was successfully achieved in a horse administered 20 mg of the EPO transgene via MFQPCR. Therefore, MFQPCR may be considered a suitable method for multiple-target detection in gene-doping control. To our knowledge, this is the first application of microfluidic qPCR (MFQPCR) for gene-doping control in horseracing.

A plug and play microfluidic platform for standardized sensitive low-input Chromatin Immunoprecipitation

Epigenetic profiling by ChIP-Seq has become a powerful tool for genome-wide identification of regulatory elements, for defining transcriptional regulatory networks and for screening for biomarkers. However, the ChIP-Seq protocol for low-input samples is laborious, time-consuming and suffers from experimental variation, resulting in poor reproducibility and low throughput. Although prototypic microfluidic ChIP-Seq platforms have been developed, these are poorly transferable as they require sophisticated custom-made equipment and in-depth microfluidic and ChIP expertise, while lacking parallelisation. To enable standardized, automated ChIP-Seq profiling of low-input samples, we constructed PDMS-based plates containing microfluidic Integrated Fluidic Circuits capable of performing 24 sensitive ChIP reactions within 30 minutes hands-on time. These disposable plates can conveniently be loaded into a widely available controller for pneumatics and thermocycling, making the ChIP-Seq procedure Plug and Play (PnP). We demonstrate high-quality ChIP-seq on hundreds to few thousands of cells for multiple widely-profiled post-translational histone modifications, together allowing genome-wide identification of regulatory elements. As proof of principle, we managed to generate high-quality epigenetic profiles of rare totipotent subpopulations of mESCs using our platform. In light of the ready-to-go ChIP plates and the automated workflow, we named our procedure PnP-ChIP-Seq. PnP-ChIP-Seq allows non-expert labs worldwide to conveniently run robust, standardized ChIP-Seq, while its high-throughput, consistency and sensitivity paves the way towards large-scale profiling of precious sample types such as rare subpopulations of cells or biopsies.Reviewer link to dataAll sequencing data has been submitted to the NCBI GEO database. Reviewer link: http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?token=klwnocicrpaxrkv&acc=GSE120673

Delay by Spin-Up of Captive Vortex

Recent application of fluidics show increasing importance with respect to signals encoded in flow pulses, in oscillators as well as in closely related devices for correcting the distorted pulse shapes. The parameters of the pulses are adjusted using the output of the fluidic circuits generating the time delays. Currently they are mostly based on the speed of the flow propagation channels. This paper focuses on a much less known delay principle, based on the dynamics of spin-up of a vortex rotating inside a closed cavity and shows some simple fluidic circuits using this principle. Apart from an experimentally investigated model, the manuscript also contains a simple theory for the captive vortex dynamics.

Time-Delay Circuits for Fluidic Oscillators and Pulse Shapers

Fluidic signals transferred between mutually communicating components of fluidic circuits are nowadays still often in the format of continuously varied value of pressure or flow rate. Especially when transported over longer distances, these simple signals may easily deteriorate due to varying properties they meet in the transmission. An example are friction losses dependent on local temperature. A solution to this signal corruption problem is to encode the signals into flow pulses. Their parameters (such as the number of pulses in a delivered pulse cluster) much less deteriorating during transfer are derived from the time delays generated in delay circuits and oscillators. This paper surveys the basic physical aspects of the fluidic pulse generation and shaping, also presents some examples of circuit design.