title: Portable, one-step, and rapid GMR biosensor platform with smartphone interface.
abstract: Quantitative immunoassay tests in clinical laboratories require trained technicians, take hours to complete with multiple steps, and the instruments used are generally immobile-patient samples have to be sent in to the labs for analysis. This prevents quantitative immunoassay tests to be performed outside laboratory settings. A portable, quantitative immunoassay device will be valuable in rural and resource-limited areas, where access to healthcare is scarce or far away. We have invented Eigen Diagnosis Platform (EDP), a portable quantitative immunoassay platform based on Giant Magnetoresistance (GMR) biosensor technology. The platform does not require a trained technician to operate, and only requires one-step user involvement. It displays quantitative results in less than 15min after sample insertion, and each test costs less than US$4. The GMR biosensor employed in EDP is capable of detecting multiple biomarkers in one test, enabling a wide array of immune diagnostics to be performed simultaneously. In this paper, we describe the design of EDP, and demonstrate its capability. Multiplexed assay of human immunoglobulin G and M (IgG and IgM) antibodies with EDP achieves sensitivities down to 0.07 and 0.33 nanomolar, respectively. The platform will allow lab testing to be performed in remote areas, and open up applications of immunoassay testing in other non-clinical settings, such as home, school, and office.
authors.affiliation: Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA.
authors.forename: Joohong
authors.initials: J
authors.lastname: Choi
authors.affiliation: Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA.
authors.forename: Adi Wijaya
authors.initials: AW
authors.lastname: Gani
authors.affiliation: Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA.
authors.forename: Daniel J B
authors.initials: DJB
authors.lastname: Bechstein
authors.affiliation: Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA.
authors.forename: Jung-Rok
authors.initials: JR
authors.lastname: Lee
authors.affiliation: School of Medicine, Division of Immunology and Rheumatology, Stanford University, Stanford, CA 94305, USA.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Utz
authors.affiliation: Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA; Department of Material Science, Stanford University, Stanford, CA 94305, USA; Geballe Laboratory for Advanced Materials, Stanford University, McCullough Building, Room 351, 476 Lomita Mall, Stanford, CA 94305-4045, USA. Electronic address: sxwang@stanford.edu.
authors.forename: Shan X
authors.initials: SX
authors.lastname: Wang
mesh_terms: D055910:Antibodies, Immobilized / Q000737:chemistry; D015374:Biosensing Techniques / Q000191:economics / Q000295:instrumentation*; D004867:Equipment Design; D006801:Humans; D007118:Immunoassay / Q000191:economics / Q000295:instrumentation*; D007074:Immunoglobulin G / Q000032:analysis; D007075:Immunoglobulin M / Q000032:analysis; D060526:Magnetic Fields; D008280:Magnetics / Q000191:economics / Q000295:instrumentation*; D058185:Magnetite Nanoparticles / Q000737:chemistry; D063731:Mobile Applications / Q000191:economics; D019095:Point-of-Care Systems; D000068997:Smartphone / Q000191:economics / Q000295:instrumentation*
chemical_list: D055910:Antibodies, Immobilized; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D058185:Magnetite Nanoparticles
keywords: GMR sensor; Magnetic nanoparticle; One-step magnetic immunoassay; Point of care; Portable and rapid diagnostics; Smartphone integration