| This work describes the development of a new portable fully automated microfluidic system that fits into the palm of a hand, to perform a magnetic bead-based sandwich immunoassay in order to detect airborne bioorganisms (such as biological warfare agents). The magnetic beads were coated with a polymer to which a dendrimer-antibody conjugate had been attached to form the basis of a “sandwich” immunoassay for sensing bio molecules. Three systems were designed and fabricated using different materials as the substrate: (1) A system was fabricated on a glass-on-silicon motherboard realized by etching the micro channels directly into a silicon wafer and capping the channels with a glass wafer by anodically bonding glass-to-silicon; (2) a system was assembled by using biocompatible silicone tubing for interconnections between the devices; and (3) a silicone polymer system was formed which has embedded micro channels in polymer.; The glass-on-silicon system consists of four collapsible reservoirs for reagent storage, made of very thin Teflon™; an array of zero dead volume “collapsible” membrane type valves; two unique magnetic curtain magnetic particle separators; a micro wire electrode or IDA (inter digitated array) for detection; a flow sensor; and a peristaltic pump consisting of three membrane type valves placed in series. The system using the biocompatible silicone tubing consists of four polyethylene reservoirs, an array of zero dead volume pinch valves, two magnetic curtain magnetic particle separators, a micro wire electrode or IDA for detection, a flow sensor and a valveless mini rotary pump to pull the reagents through the microfluidic system. The silicone polymer system consists of four polyethylene reservoirs, an array of zero dead volume pinch valves, two magnetic curtain magnetic particle separators, an IDA for detection and a valveless mini rotary pump to pull the reagents through the microfluidic system. All these systems have their associated electronics. This work precedes the next step, which is an all MEMS monolithic system “on-a-chip”, although it already has the smallest working components achieved in this multi-team project.; This work was funded by the Microsystems Technology Office of the Defense Advanced Research Project Agency (DARPA-MicroFlumes Program) under contract AF F30602-97-2-0102. |
