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We present a simple and robust microfabrication technique to create three-dimensional (3D) tapered polydimethylsiloxane (PDMS) channels. Tapered photoresist structures were fabricated by single-step lithography and thermal reflowing process, and the topography of the structures was controlled by varying design parameters, e.g., channel widths and length. Two half funnel-shaped PDMS replicas were combined to realize a 3D funnelshaped PDMS structure. Human umbilical vein endothelial cells (HUVECs) were cultured in the 3D funnel channel to form an artificial vessel network. We believe that the 3D topographic structures with controlled curvatures would be useful in many scientific and engineering fields, including lab-on-a-chip devices and bioinspired platforms.

We present the development of an automated microfluidic platform that is capable of creating logarithmic serial dilution by adapting pneumatically actuated microvalves. A valve-assisted droplet manipulator integrated with a peristaltic mixer allowed the accurate formation of droplets with controlled sizes and the dilution of reagent sequentially. Hence, serial dilution with flexible dilution factors was obtained in a series of nanoliter-scale droplets. We validated the mixing efficiency and droplet generating performance of the chip at various operating conditions and demonstrated an example of logarithmic serial dilution with two different dilution factors. The microfluidic droplet serial dilutor could be used as an analytical tool to evaluate various complex chemical and biochemical reactions.

Standardized high-throughput devices for microfluidic cell cultures are necessary to translate discoveries made in academia to applications in pharmaceutical industry. Here we present a platform with integrated pneumatic valves for standardized parallelization of multichamber chips (SPARC). In total, 192 chambers divided over three microfluidic building blocks (MFBBs) can be filled and purged with spatial and temporal independence. The dimensions of both the MFBB and the platform are standardized and thus compatible with common lab equipment. We characterize the valves at different pumping and gate pressures and show that the MFBBs are suitable for culturing human umbilical vein endothelial cells (HUVECs).

In this research, we aim to characterize extracellular vesicles(EVs) with Confocal Raman spectroscopy to reveal relevant spectral lines that signify differences between EVs derived from different cell lines. In the first stage we performed confocal Raman measurements on various EV samples. For these experiments, a 50 µl droplet of EVs was placed in a hollow area on a slide which was covered with a thin glass disk. Both the slide and the disk consist of borosilicate glass. A well-defined laser beam was focused on the sample inside the cavity. Clusters of EVs were trapped in the focal volume by the single-beam gradient force. In parallel we are trying to increase the signal to noise ratio (SNR) by increasing the EV density and to collect signal only from desired EVs. We developed a PDMS microchannel device to attract specific EVs and enrich its concentration at the surface area of the microchannel device.

Introduction: Genetic and phenotypic characterization of Circulating Tumor Cells (CTC) offer the opportunity for a “real time liquid biopsy”. However, heterogeneity and rarity of CTC command the need for individual cell characterization. Following an enrichment procedure of CTC from blood, the identification, isolation and manipulation of single CTC for further analysis without cell loss remains challenging. Here, we present microfluidic devices for parallel single cell whole genome amplification (psc WGA) and parallel probing of drug response of single cancer cells (psc probing). Method: Microfluidic devices were designed using AUTOCAD software, and fabricated using PDMS multilayer soft-lithography. Cells from the SKBR-3 and MCF-7 breast cancer cell lines were used in the devices and identified using fluorescence microscopy after immunofluorescence staining. For pscWGA, the GE Single Cell GenomiPhi DNA Amplification kit was used under isothermal conditions. Results: In the 1st scWGA device, single cancer cells were addressed in 16 individual reaction chambers, subsequently lyzed, and their DNA amplified on a chip. We successfully amplified DNA of single cancer cells in a ca. 23 nanoliter reaction volume. 1,000-fold amplified DNAs were validated using qPCR targeting a set of genes on different chromosomes. For WGA of CTC present in a large number of other cells, we developed a 2nd scWGA platform by combining a self-sorting microwell cell sorter and a microfluidic device. After filtration of a cell suspension using a microwell plate, cancer cells were identified using fluorescence microscopy at the bottom of the plate. Cells of interest were subsequently punched into the open-well structures of the microfluidic device for further analysis. The lysis and WGA reaction buffers were loaded using peristaltic pumping of integrated micro-valves. After cell lysis, DNA was amplified in the open-well reaction chamber. For validation ∼ 100 ng of DNA was pipetted out of the well. We also developed microfluidic devices to study drug-dose response of single cancer cells. This device is capable of capturing single cells, dosing various concentrations of drugs and exposing the cells to the drugs. We optimized the capturing efficiency using different sizes of beads (3 μm, 6 μm, and 15 μm) as well as MCF-7 cells. We demonstrated that single cancer cells could be exposed to different drug candidates in the reagent chambers and their response measured. Conclusion: We successfully developed various microfluidic devices for individual cell characterization to be applied for CTC analysis. For genetic make-up, whole genome amplification of single cells either in suspension or in a self-sorting microwell plate was demonstrated. On-chip cell lysis and DNA amplification were performed and validated by qPCR targeting specific genes. In addition microfluidic devices were designed and tested to investigate single cell response to cancer drugs.

We show the development of a microfluidic platform that is capable of performing 36 parallel reactions with 36 combinations of the concentrations of two reagents. With the device, we obtained a 3D enzymatic reaction plot of horseradish peroxidase (HRP) with Amplex Red (AR) and hydrogen peroxide (H2O2) in a nanoliter scale volume. The system could be used as a fast analytical tool to evaluate various chemical and biochemical reactions especially where two or more reagents interact with each other.

We present a novel microfluidic system for the pH-gradient focusing of proteins with the integration of 16 parallel micro-mixers, a micro-column, and a multiplexer. In this work we successfully achieved the creation of 16 non-linear gradients and the generation of a solid-phase micro-column for the realization of anion exchange chromatography on a single chip. With the device we demonstrated the separation of a protein mixture of R-phycoerythrin and FITC-BSA based on pH-gradient chromatofocusing.