Methods and apparatus for measuring analytes using large scale FET arrays
First Claim
1. An apparatus comprising:
- a sensor array of at least 105 sensors formed in the substrate, the sensors having a pitch distance of not more than 10 microns;
at least one of the sensors in the array defining a chemFET having a gate oxide with a characteristic thickness, a floating gate, and a characteristic threshold voltage;
wherein the characteristic threshold voltage of the chemFET is affected by a trapped charge; and
wherein the characteristic thickness of the gate oxide is selected to reduce the trapped charge in the sensor by allowing a trapped charge to pass through the gate oxide onto the substrate.
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Abstract
Methods and apparatus relating to very large scale FET arrays for analyte measurements. ChemFET (e.g., ISFET) arrays may be fabricated using conventional CMOS processing techniques based on improved FET pixel and array designs that increase measurement sensitivity and accuracy, and at the same time facilitate significantly small pixel sizes and dense arrays. Improved array control techniques provide for rapid data acquisition from large and dense arrays. Such arrays may be employed to detect a presence and/or concentration changes of various analyte types in a wide variety of chemical and/or biological processes. In one example, chemFET arrays facilitate DNA sequencing techniques based on monitoring changes in hydrogen ion concentration (pH), changes in other analyte concentration, and/or binding events associated with chemical processes relating to DNA synthesis.
383 Citations
20 Claims
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1. An apparatus comprising:
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a sensor array of at least 105 sensors formed in the substrate, the sensors having a pitch distance of not more than 10 microns; at least one of the sensors in the array defining a chemFET having a gate oxide with a characteristic thickness, a floating gate, and a characteristic threshold voltage; wherein the characteristic threshold voltage of the chemFET is affected by a trapped charge; and wherein the characteristic thickness of the gate oxide is selected to reduce the trapped charge in the sensor by allowing a trapped charge to pass through the gate oxide onto the substrate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A detection system, comprising:
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an array of at least 105 FET sensors forming a FET sensor array arranged in columns and rows, each FET sensor separated from an adjacent FET sensor by a pitch distance of not more than 10 microns; an array of wells formed on a substrate, a plurality of the wells in the array of wells corresponding to a plurality of sensors in the FET array; wherein the array of wells is not more than 7 mm by 7 mm in surface area; and wherein at a first well is coupled to a first FET sensor such that a reaction by-product in the first well is communicated to the first sensor. - View Dependent Claims (16, 17, 18, 20)
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19. A detection system, comprising:
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a control circuit in communication with a CMOS detector formed in a substrate, the CMOS detector having an array of at least 105 sensors arranged to correspond with and communicate with an array of detection wells in which the wells are arranged to have a pitch distance of about 10 microns or less; and a gate oxide layer interposed between a source electrode and a floating gate of a first sensor of the array; wherein the characteristic thickness of the gate oxide is selected to reduce a trapped charge in the sensor by allowing a trapped charge to pass through the gate oxide onto the substrate.
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Specification