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[en] In this paper we present a novel fabrication technique that utilizes polycaprolactone (PCL) as a bonding medium due to its low melting temperature property. PCL is biodegradable polyester with a melting point of 60 °C, and a glass transition temperature of −60 °C [1–10]. It is used as a rapid bonding medium in the fabrication process that readily produces complete microfluidic chips. The microchannels are produced via laser ablation micromachining and thermal embossing, followed by bonding with PCL. The PCL is uniformly coated on a piece of polymer sheet to produce a thin film on its surface. A complete microfluidic channel is formed by enclosing the open channel with the PCL-coated polymer piece. This fabrication technique lends itself readily to various polymers, such as (poly)methylmethacrylate (PMMA), polycarbonate (PC), polyetherimide (PEI) and poly(ethylene terephthalate) (PETE), facilitating device production for a variety of application, even permitting hybrid polymer chips. The bonding was performed rapidly at 60 °C. This approach provides a more direct method to generate hard polymer microfluidic chips than classical techniques and is therefore highly amendable to rapid prototyping. This work also explores the use of PCL as an alternative approach to making simple, cost-effective universal adhesive for bonding interconnects. Bonding is performed at 60 °C, by placing the adhesive layer in between an interconnect port and a microchip. This method allows for connections to be made easily and quickly. (paper)
[en] We demonstrate that micron-scale graphene field-effect transistor biosensors can be fabricated in a scalable fashion from large-area chemical vapor deposition derived graphene. We electrically detect the real-time binding and unbinding of a protein biomarker, thrombin, to and from aptamer-coated graphene surfaces. Our sensors have low background noise and high transconductance, comparable to exfoliated graphene devices. The devices are reusable and have a shelf-life greater than one week. (paper)
[en] A critical barrier to the routine use of nanomaterials is the tedious, expensive means of their synthesis. Microreaction technology takes advantage of the large surface area-to-volume ratios within microchannel structures to accelerate heat and mass transport. This accelerated transport allows for rapid changes in reaction temperatures and concentrations leading to more uniform heating and mixing which can have dramatic impacts on macromolecular yields and nanoparticle size distributions. Benefits of microreaction technology include higher yield and reactant conversion, better energy efficiency and less by-product generation. Microreactors can help minimize the environmental impact of nanoproduction by enabling solvent free mixing, integrated separation techniques and reagent recycling. The possibility of synthesizing nanomaterials in the required volumes at the point-of-use eliminates the need to store and transport potentially hazardous materials and provides the flexibility for tailoring complex functional nanomaterials. Recognizing these benefits for nanosynthesis, continuous flow microreactors have been used by several research groups to synthesize and characterize nanomaterials. An overview of these efforts and issues related to scale up and other post synthesis processes such as separation and deposition are presented in this paper.