title: Nanoelectronic impedance detection of target cells.
abstract: Detection of cells is typically performed using optical fluorescence based techniques such as flow cytometry. Here we present the impedance detection of target cells using a nanoelectronic probe we have developed, which we refer to as the nanoneedle biosensor. The nanoneedle consists of a thin film conducting electrode layer at the bottom, an insulative oxide layer above, another conductive electrode layer above, and a protective oxide above. The electrical impedance is measured between the two electrode layers. Cells captured on the surface of the nanoneedle tip results in a decrease in the impedance across the sensing electrodes. The basic mechanisms behind the electrical response of cells in solution under an applied alternating electrical field stems from modulation of the relative permittivity at the interface. In this paper we discuss, the circuit model, the nanofabrication, and the testing and characterization of the sensor. We demonstrate proof of concept for detection of yeast cells with specificity. We envision the sensor presented in this paper to be combined with microfluidic pre-concentration technologies to develop low cost point-of-care diagnostic assays for the clinical setting.
authors: Center for Integrated Systems, Department of Electrical Engineering, Stanford University, Stanford, California; Stanford Genome Technology Center, 855 California Ave., Palo Alto, California, 94304. rahimes@stanford.edu.
authors: Rahim
authors: R
authors: Esfandyarpour
authors: Mehdi
authors: M
authors: Javanmard
authors: Zahra
authors: Z
authors: Koochak
authors: James S
authors: JS
authors: Harris
authors: Ronald W
authors: RW
authors: Davis
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D002468:Cell Physiological Phenomena; D017097:Electric Impedance; D046210:Microfluidic Analytical Techniques; D036103:Nanotechnology; D015003:Yeasts / Q000302:isolation & purification
keywords: biosensing; cell detection; impedance detection; nanobiotechnology; nanotechnology