Liquids on-chip describes a reagent storage concept for disposable pressure driven Lab-on-Chip (LoC) devices, which enables liquid storage in reservoirs without additional packaging. On-chip storage of liquids can be considered as one of the major challenges for the commercial break through of polymer-based LoC devices. Especially the ability for long-term storage and reagent release on demand are the most important aspects for a fully developed technology. On-chip storage not only replaces manual pipetting, it creates numerous advantages: fully automated processing, ease of use, reduction of contamination and transportation risks. Previous concepts for on-chip storage are based on liquid packaging solutions (e.g. stick packs, blisters, glass ampoules), which implicate manufacturing complexity and additional pick and place processes. That is why we prefer on-chip storage of liquids directly in reservoirs. The liquids are collected in reservoirs, which are made of high barrier polymers or coated by selected barrier layers. Therefore, commonly used polymers for LoC applications as cyclic olefin polymer (COP) and polycarbonate (PC) were investigated in the context of novel polymer composites. To ensure long-term stability the reservoirs are sealed with a commercially available barrier film by hot embossing. The barrier film is structured by pulsed laser ablation, which installs rated break points without affecting the barrier properties. A flexible membrane is actuated through pneumatic pressure for reagent release on demand. The membrane deflection breaks the barrier film and leads to efficient cleaning of the reservoirs in order to provide the liquids for further processing.

We present a technology platform suitable for the mass production of laboratory-on-a-chip devices made of polymers with integrated active and passive components. The presented microfluidic platform with integrated valves and pumps for active flow management is realized with three layers consisting of two polymer parts separated by a thin elastic TPE (thermoplastic elastomer) membrane welded together in one step. The elastic TPE membrane acts as an integrated deflectable membrane layer between the two outer polymer layers, each made of a weldable thermoplastic polymer (polycarbonate). Valving is realized by applying pressure in a displacement chamber above a hydraulic channel causing the membrane to deform and to seal the channel. A pump is fabricated using a displacement chamber with a valve on the inlet and outlet. The presented components, namely valve and pump, show excellent behavior regarding response time, sealing quality, and pump rate needing only a low actuation pressure. The three-layer-stack is joined in a single process step by using laser welding, creating devices with high mechanical stability. This production technology fulfills the requirements of a high volume fabrication at high quality and has the potential to manufacture cost-efficient and reliable laboratory-on-a-chip systems. The used materials show a high chemical resistance against a broad range of commonly used liquids and good optical characteristics for the use in μTAS. This consistent technological approach represents a flexible platform for microfluidics with active components to be used in complex applications.

On-chip storage of liquids is one of the major challenges of polymer-based lab-on-a-chip (LoC) devices. To ensure long-term storage of even highly volatile reagents in polymer disposal LoC cartridges, robust reagent storage concepts are necessary. Tubular bags, so-called stick packs, are widely used in the packaging industry. They offer sufficient vapor barrier properties for liquid storage. Here we present a polymer multilayer LoC-stack with integrated stick packs for the long-term storage of liquid reagents required for diagnostic applications. The storage concept fulfils two main requirements: firstly, the long-term storage of reagents in stick packs without significant losses or interaction with the surroundings and secondly, the on-demand release of liquids, which is realized by the delamination of a stick pack’s peel seam through pneumatic pressure. Furthermore, effects on the opening behavior of stick packs through accelerated aging were investigated after different storage conditions to proof repeatability. This concept enables on-chip storage of liquid reagents at room temperature and allows the implementation in different pressure driven LoC devices or similar applications. Since liquid storage in stick packs is well-established, emerging fields such as lab-on-a-chip combined with novel reagent release mechanisms should be of great interest for the commercialization of life science products.

In this paper we present our results on polymer permeability control by organo-SiO x -layers (Aquacer©, Lipocer© 1 ). The goal of our investigations is to use transparent polymers for optical MEMS-packaging. In contrast to costly MEMS-packages made of glass, thermoplastic polymers provide high transparency, low costs and good processability. Their main drawbacks regarding their usage for MEMS-packaging are their high thermal expansion coefficient and their high permeability. On this account, a transparent gas barrier coating with high tolerance against thermal expansion is needed. The organic content in the investigated silicon-oxide-layers induces higher ductility and therefore reduce crack susceptibility in comparison to inorganic silicon-oxide.