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One way to improve the sensitivity and throughput of miniaturized biomolecular assays is to integrate microfluidics to enhance the transport efficiency of biomolecules to the reaction sites. Such microfluidic integration requires bonding of a prefabricated microfluidic gasket to an assay surface without destroying its biological activity. In this paper we address the largely unmet challenge to accomplish a proper seal between a microfluidic gasket and a protein surface, with maintained biological activity and without contaminating the surface or blocking the microfluidic channels. We introduce a novel dual cure polymer resin for the formation of microfluidic gaskets that can be room-temperature bonded to a range of substrates using only UVA light. This polymer is the first polymer that features over a month of shelf life between the structure formation and the bonding, moreover the fully cured polymer gaskets feature the following set of properties suitable for microfluidics: high stiffness, which prevents microfluidic channel collapse during handling; very limited absorption of biomolecules; and no significant leaching of uncured monomers. We describe the novel polymer resin and its characteristics, study through FT-IR, and demonstrate its use as microfluidic well-arrays bonded onto protein array slides at room temperature followed by multiplexed immunoassays. The results confirm maintained biological activity and show high repeatability between protein arrays. This new approach for integrating microfluidic gaskets to biofunctionalised surfaces has the potential to improve sample throughput and decrease manufacturing costs for miniaturized biomolecular systems. [ABSTRACT FROM AUTHOR]

In this paper we present a reusable, chemically inert, multichannel Chip-to-World-Interface (CWI). The concept of this interface is based on a force fit connection similar to the hollow screw connectors known from high-performance liquid chromatography (HPLC) instruments. It allows contamination free connection of up to 100 thermoplastic tubes to microfluidic chips made from various materials e.g., epoxy polymers, glass and polydimethylsiloxane (PDMS). The spacing of the tubes is fixed whereas the outer dimensions of the CWI can be adapted to the microfluidic chip it should be used with. We demonstrate that such a CWI with 100 tubes is pressure-tight up to (at least) 630 kPa (6.3 bar) pressure and the connection easily sustains flow rates above 4 ml min−1. The presented CWI is designed such that the fluid probed in the microfluidic chip is in direct contact only with the tube material and the material from which the microfluidic chip is made. This not only enables fluid transport without dead volume, it also ensures that CWI itself will not be contaminated or contaminate the samples being probed. Using polytetrafluoroethylene (PTFE, Teflon®) tubing we demonstrate that the CWI can even be used with harsh organic solvents such as dichloromethane or dimethylformamide during continuous solvent probing over several hours without damage to the CWI or leakage. This CWI therefore effectively allows using almost all types of organic solvents in microfluidic applications. [ABSTRACT FROM AUTHOR]

The generation and sensation of mechanical force plays a role in many dynamic biological processes, including touch sensation. This paper presents a two-axis micro strain gauge force sensor constructed from multiple layers of SU-8 and metal on quartz substrates. The sensor was designed to meet requirements for measuring tactile sensitivity and interaction forces exerted during locomotion by small organisms such as the nematode Caenorhabditis elegans. The device is transparent and compatible with light microscopes, allowing behavioral experiments to be combined with quantitative force measurements. For the first time, we have characterized the scale of interaction forces generated in wild-type C. elegans in probing and responding to their environment during locomotion. The device features sub-microN force resolution from 1 Hz to 1 kHz, >25 microN range, kHz acquisition rates and biocompatibility.

A new micropallet array platform for adherent cell colony sorting has been developed. The platform consisted of thousands of square plastic pallets, 270 μm by 270 μm on each side, large enough to hold a single colony of cells. Each pallet included a magnetic core, allowing them to be collected with a magnet after being released using a microscope mounted laser system. The micropallets were patterned from 1002F epoxy resist and were fabricated on translucent, gold coated microscope slides. The gold layer was used as seed for electroplating the ferromagnetic cores within every individual pallet. The gold layer also facilitated the release of each micropallet during laser release. This array allows for individual observation, sorting and collection of isolated cell colonies for biological cell colony research. In addition to consistent release and recovery of individual colonies, we demonstrated stable biocompatibility and minimal loss in imaging quality compared to previously developed micropallet arrays. [ABSTRACT FROM AUTHOR]