title: Low-cost photolithographic fabrication of nanowires and microfilters for advanced bioassay devices.
abstract: Integrated microfluidic devices with nanosized array electrodes and microfiltration capabilities can greatly increase sensitivity and enhance automation in immunoassay devices. In this contribution, we utilize the edge-patterning method of thin aluminum (Al) films in order to form nano- to micron-sized gaps. Evaporation of high work-function metals (i.e., Au, Ag, etc.) on these gaps, followed by Al lift-off, enables the formation of electrical uniform nanowires from low-cost, plastic-based, photomasks. By replacing Al with chromium (Cr), the formation of high resolution, custom-made photomasks that are ideal for low-cost fabrication of a plurality of array devices were realized. To demonstrate the feasibility of such Cr photomasks, SU-8 micro-pillar masters were formed and replicated into PDMS to produce micron-sized filters with 3-4 µm gaps and an aspect ratio of 3. These microfilters were capable of retaining 6 µm beads within a localized site, while allowing solvent flow. The combination of nanowire arrays and micro-pillar filtration opens new perspectives for rapid R&amp;D screening of various microfluidic-based immunoassay geometries, where analyte pre-concentration and highly sensitive, electrochemical detection can be readily co-localized.
authors.affiliation: Nanomaterials Optoelectronics Laboratory, Polymer Program, University of Connecticut, Storrs, CT 06269, USA. nhi.doan@uconn.edu.
authors.forename: Nhi M
authors.initials: NM
authors.lastname: Doan
authors.affiliation: Nanomaterials Optoelectronics Laboratory, Polymer Program, University of Connecticut, Storrs, CT 06269, USA. liangliang.qiang@gmail.com.
authors.forename: Liangliang
authors.initials: L
authors.lastname: Qiang
authors.affiliation: Nanomaterials Optoelectronics Laboratory, Polymer Program, University of Connecticut, Storrs, CT 06269, USA. zhe.li@uconn.edu.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Li
authors.affiliation: Nanomaterials Optoelectronics Laboratory, Polymer Program, University of Connecticut, Storrs, CT 06269, USA. sagar@bio-orasis.com.|Biorasis Inc., 23 Fellen Road, Storrs, CT 06268, USA. sagar@bio-orasis.com.
authors.forename: Santhisagar
authors.initials: S
authors.lastname: Vaddiraju
authors.affiliation: Department of Chemistry, University of Connecticut, Storrs, CT 06269, USA. greg.bishop@uconn.edu.
authors.forename: Gregory W
authors.initials: GW
authors.lastname: Bishop
authors.affiliation: Department of Chemistry, University of Connecticut, Storrs, CT 06269, USA. james.rusling@uconn.edu.|Institute of Materials Science, University of Connecticut, Storrs, CT 06269, USA. james.rusling@uconn.edu.|Department of Cell Biology, University of Connecticut Health Center, Farmington, CT 062032, USA. james.rusling@uconn.edu.|School of Chemistry, National University of Ireland, Galway, Ireland. james.rusling@uconn.edu.
authors.forename: James F
authors.initials: JF
authors.lastname: Rusling
authors.affiliation: Nanomaterials Optoelectronics Laboratory, Polymer Program, University of Connecticut, Storrs, CT 06269, USA. papadim@ims.uconn.edu.|Department of Chemistry, University of Connecticut, Storrs, CT 06269, USA. papadim@ims.uconn.edu.|Institute of Materials Science, University of Connecticut, Storrs, CT 06269, USA. papadim@ims.uconn.edu.
authors.forename: Fotios
authors.initials: F
authors.lastname: Papadimitrakopoulos
mesh_terms: D000535:Aluminum / Q000737:chemistry*; D002857:Chromium / Q000737:chemistry; D007118:Immunoassay / Q000295:instrumentation*; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D053770:Nanowires / Q000737:chemistry
chemical_list: D002857:Chromium; D000535:Aluminum