Chemoreceptive semiconductor structure

Abstract

A field effect transistor has a floating gate with an extended portion. A selectively chemoreceptive finger or layer is electrostatically coupled to the extended portion of the floating gate, and induces a voltage on the gate in response to selected chemicals or other conditions affecting the finger. The voltage on the gate modulates current flowing between a source and a drain of the transistor, effectively sensing the presence of the selected chemicals or conditions. In one embodiment, multiple chemoreceptive fingers are electrostatically coupled to the extended portion of the floating gate. In a further embodiment, an array of such field effect transistors provide a sensor for multiple conditions.

1 - 4 . (canceled)  
   
   
       5 . A sensor comprising: 
 a field effect transistor having a source, drain and floating gate, wherein the floating gate has an extended portion; and    multiple selectively chemoreceptive fingers electrostatically coupled to the extended portion of the floating gate.    
   
   
       6 . The sensor of  claim 5  wherein the selectively chemoreceptive fingers are electrically isolated from the extended portion of the floating gate.  
   
   
       7 . The sensor of  claim 6  wherein the electrical isolation is provided by a nitride plug.  
   
   
       8 . The sensor of  claim 5  and further comprising a microfluidic channel coupled to at least one of the chemoreceptive fingers for selectively exposing such chemoreceptive fingers to fluid.  
   
   
       9 . The sensor of  claim 8  and further comprising a separate microfluidic channel for each chemoreceptive finger for selectively exposing such chemoreceptive fingers to different fluids.  
   
   
       10 - 15 . (canceled)  
   
   
       16 . A sensor comprising: 
 a field effect transistor having a source, drain and floating gate, wherein the floating gate has an extended portion;    a chemoreceptive layer capacitively coupled to the extended portion of the floating gate; and    a microfluidic channel coupled to the chemoreceptive layer.    
   
   
       17 . The sensor of  claim 16  and further comprising one or more resistors coupled to the microfluidic channels.  
   
   
       18 . The sensor of  claim 17 , wherein the resistors provide a reference potential to the microfluidic channels.  
   
   
       19 . A sensor comprising: 
 an array of field effect transistors, each having a source, drain and floating gate, wherein the floating gate has an extended portion with a chemoreceptive layer electrostatically coupled to the extended portion of the floating gate.    
   
   
       20 . The sensor of  claim 19  and further comprising a controller coupled to the field effect transistors to measure current flowing between the source and drain of each transistor.  
   
   
       21 . The sensor of  claim 20  and further comprising a transponder coupled to the controller for communicating with other devices.  
   
   
       22 . A method of sensing chemicals comprising: 
 providing a sample to a chemoreceptive layer supported by an extended electrostatically coupled gate;    inducing a voltage on the extended gate; and    modulating current through a source and drain based on the induced voltage on the floating gate.    
   
   
       23 - 25 . (canceled)