Method and apparatus for identifying defects in a chemical sensor arraymethod and apparatus for identifying defects in a chemical sensor array

Abstract

In one implementation, a method for operating an apparatus is described. The method includes applying a bias voltage to place a transistor of a reference sensor in a known state. The reference sensor is in an array of sensors that further includes a chemical sensor coupled to a reaction region for receiving at least one reactant. The method further includes acquiring an output signal from the reference sensor in response to the applied bias voltage. The method further includes determining a defect associated with the array if the output signal does not correspond to the known state.

What is claimed: 
     
         1 . A semiconductor device, comprising:
 an array of field-effect transistor (FET) sensors arranged in a plurality of rows and a plurality of columns, the array including
 a plurality of chemical sensors, each chemical sensor coupled to a corresponding reaction region for receiving at least one reactant, and 
 a plurality of reference sensors, each reference sensor including a reference transistor with a first terminal directly coupled to a first reference select switch to apply a bias voltage to the reference transistor and directly coupled to a second reference select switch to couple the first terminal of the reference transistor to a column line; and 
   an access circuit for accessing the chemical sensors and the reference sensors, wherein the access circuit includes a plurality of reference lines coupled to a gate terminal of each reference transistor in a corresponding set of reference sensors;   
     
     
         2 . The semiconductor device of  claim 1 , wherein each chemical sensor is a chemically-sensitive transistor. 
     
     
         3 . The semiconductor device of  claim 1 , wherein the bias voltage is sufficient to place the reference transistor in one of an on state or an off state. 
     
     
         4 . The semiconductor device of  claim 1 , wherein the chemical sensor generates a sensor signal in response to a chemical reaction occurring within the reaction region. 
     
     
         5 . The semiconductor device of  claim 1 , wherein a chemical reaction in the reaction region is a sequencing reaction. 
     
     
         6 . The semiconductor device of  claim 1 , wherein the chemical sensor and the reference sensor share the access circuit.