Octavian Florescu Prof Bernard E Boser BEB 17
Octavian Florescu, Prof. Bernard E. Boser BEB 17 Wireless CMOS Immuno. Sensor • Magnetically Labeled Antigens • ELISA-like Chemistry • Standard CMOS Substrate • Wireless © 2005 University of California Project Goals • High specificity • Portable/self contained • Simple Protocol • Develop at-home or in-the-field diagnostic tool Prepublication Data Fall 2005
Magnet Bead Binding ~ 1 mm Magnetic Bead Antibody Target Antigen Silicon Dioxide Hall Sensor • Small magnetite beads can be coated with many biologically active materials, including monoclonal antibodies. • Target antigens immobilize beads for detection. © 2005 University of California Prepublication Data Fall 2005
Magnet Field Chemagen 5 -mm bead Magnetic Bead B (T) B Wafer Plane Hx y h x (mm) y (mm) B Z • BZ is has opposite polarity peaks spaced by approximately the bead diameter. • BZ, max decays with the cube of the bead height h. © 2005 University of California Prepublication Data Fall 2005
CMOS Hall Sensor Drain 1 Drain 2 Thin Oxide Boundary Field Oxide I B 6 mm G = geometric factor (0. 65) Source 6 mm • Device dimensions selected to match magnetic field perturbation from a single 5 -mm bead. • Smaller devices have higher overhead of nonsensing area. © 2005 University of California Prepublication Data Fall 2005
Hall Sensor Array with Magnetic Beads Electronic Interface Magnetic Beads Sensor Array • Array provides quantization (range of detection) while also allowing each element to match to the bead size. © 2005 University of California Prepublication Data Fall 2005
1. 4 mm Sensor Array ADC Amp Clock Power + Bias • Layout of the Wireless © 2005 University of California Prepublication Data Fall 2005 Immuno. Sensor
Wireless Interface Vial containing Blood/Serum The Immuno. Sensor communicates with the rest of the system wirelessly Immuno. Sensor is placed in vial Power and signals are inductively coupled to the Immuno. Sensor © 2005 University of California Prepublication Data Fall 2005
Results: • 12 patients from Nicaragua were tested for Dengue, using the reference ELISA (also from Nicaragua) and the first generation flipchip Immunosensor. The actual assay chemistry is Human Ig. G anti-body against Dengue, in a capture format. • These results represent the first magnetic bead assay that used serum, rather than purified protein. When comparing the Immunosensor output versus the ELISA optical density, it was found that their normalized standard deviations from their desired responses were 0. 027 and 0. 0052 respectively. © 2005 University of California Prepublication Data Fall 2005
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