University of Illinois

Purdue Research Foundation

Eric M Salm

Rashid Bashir

Yi-Shao Liu

Bobby Reddy, Jr

Nicholas Watkins

Woo-Jin Chang

Muhammad Ashraf Alam

Carlos Duarte-Guevara

Vikhram Vilasur Swaminathan

Carlos Eduardo Duarte Guevara

Provided are methods and devices for the label free detection of analytes in solution, including analytes suspended in a biological fluid. A field effect transistor (FET) is positioned in close proximity to a paired set of reference electrodes and the reference electrodes electrically biased to provide desalting and a stable gate voltage to the FET. In this manner, charged ions are depleted in the sensing region of the sensor and device sensitivity to analyte detection improved by the removal of charge that otherwise interferes with measurement. Also provided are methods and systems providing increased in reference electrode surface area and/or decrease in droplet volume to further improve label-free detection of analytes.

Label free analyte detection by electronic desalting and field effect transistors

Provided herein are methods and devices for rapidly and accurately heating fluid droplets surrounded by a gas-phase medium, such as air. Sub-nanoliter fluid droplets can be rapidly heated by nanoscale field effect transistors via microwave heating by an applied AC voltage to the FET. The heating is in a well-defined interior portion of the fluid droplet, with minimal heating of the outer portion of the fluid droplet, thereby minimizing evaporation. In this manner, rapid thermal cycling is possible, including independently and in parallel for a plurality of droplets. Accordingly, the methods and devices provided herein are used in point-of-care detection such as by PCR that is high speed, robust and of low cost.

Thermal control of droplets by nanoscale field effect transistors

Provided are methods and devices for label-free detection of nucleic acids that are amplified by polymerase chain reaction. A solution containing the components necessary for a PCR is introduced to a microfluidic amplification chamber and an electric field applied to a confined region in which PCR occurs. PCR product generated in the confined region is detected by measuring an electrical parameter that is, for example, solution impedance. The devices and methods provided herein are used, for example, in assays to detect one or more pathogens or for point-of-care tests. In an aspect, the PCR product is confined to droplets and the assay relates to detecting an electrical parameter of a flowing droplet, thereby detecting PCR product without a label. In an aspect, the PCR occurs in the droplet.

Label free detection of nucleic acid amplification

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Champaign, IL, United States of America

Eric M Salm