Chemical synthesis and sensing in inexpensive thread-based microdevices

Many common and inexpensive materials, such as, paper, fabric and thread are currently being explored as alternate substrates for low-cost and field-based sensing applications. While these substrates have primarily been utilized to develop low-cost diagnostic devices, it is important to study whether these materials are suitable for more general chemical sensing applications. Here, we report chemical syntheses (inorganic and organic) and sensing using threads as microchannels. We first characterized the liquid transport through thread channels and then measured typical sample losses due to adsorption and evaporation. Next, we demonstrated synthesis of ferric hydroxide in a Y-geometry thread reactor and detected the product by colorimetry. Our low-cost device gave a product yield of 84% compared to a test tube-based synthesis. We also synthesized (with ∼72% yield) and detected colorless 2,4-dichloro-N-(2-morpholinoethyl) benzamide in an attempt to demonstrate an organic reaction in a thread device. Finally, we successfully detected bovine serum albumin and the glucose present in blood plasma as examples of detection of chemical substances relevant in diagnostics. Our results indicate that cotton and silk threads are indeed suitable materials for incorporation into field-deployable disposable chemical reaction and sensing systems.