Incorporating cmos integrated circuits in the design of affinity-based biosensor systems

Abstract

A biosensor system incorporating CMOS integrated circuits. In one type of biosensor system, the biosensor system includes a complementary metal-oxide-semiconductor (“CMOS”) integrated circuit. The biosensor system further includes an optical filter fabricated on the CMOS integrated circuit. Additionally, a plurality of capturing probes is optically coupled to the CMOS integrated circuit. Alternatively, another type of biosensor system includes a silicon substrate. The alternative biosensor system further includes active devices fabricated on the silicon substrate. Additionally, the alternative biosensor system includes a plurality of metal layers stacked on top of the active devices. Furthermore, the alternative biosensor system includes a passivation layer covering a top metal layer, where the passivation layer includes an opening configured to expose the top metal layer, where the opening is used as a sensing electrode. Additionally, the alternative biosensor system includes a plurality of probes attached to the sensing electrode.

1 . A biosensor system, comprising:
 a complementary metal-oxide-semiconductor integrated circuit, wherein said complementary metal-oxide-semiconductor integrated circuit comprises a silicon substrate and a dielectric layer on said silicon substrate;   an optical filter fabricated on said complementary metal-oxide-semiconductor integrated circuit; and   a plurality of capturing probes optically coupled to said complementary metal-oxide-semiconductor integrated circuit.   
     
     
         2 . The biosensor system as recited in  claim 1 , wherein said optical filter prohibits light scattering. 
     
     
         3 . The biosensor system as recited in  claim 1 , wherein said optical filter guides two-dimensional signals along a vertical direction of its fibers. 
     
     
         4 . The biosensor system as recited in  claim 1  further comprising:
 a fiber-optical faceplate positioned on said optical filter, wherein said plurality of capturing probes are optically coupled to said complementary metal-oxide-semiconductor integrated circuit using said fiber-optical faceplate.   
     
     
         5 . The biosensor system as recited in  claim 4 , wherein a thickness of said fiber-optical faceplate is between 0.5 millimeters and 3.0 millimeters. 
     
     
         6 . The biosensor system as recited in  claim 4 , wherein an exposed surface of said fiber-optical faceplate is silicon dioxide. 
     
     
         7 . The biosensor system as recited in  claim 1 , wherein said complementary metal-oxide-semiconductor integrated circuit comprises a biosensor pixel fabricated in said silicon substrate, wherein said biosensor pixel comprises:
 a capacitive transimpedance amplifier used to create a photocurrent integrator, wherein said capacitive transimpedance amplifier comprises a photodiode.   
     
     
         8 . The biosensor system as recited in  claim 7 , wherein a photocurrent generated in said photodiode is directly integrated on a photodiode capacitor. 
     
     
         9 . The biosensor system as recited in  claim 7 , wherein said biosensor pixel further comprises:
 an analog-to-digital converter configured to compare an output of said capacitive transimpedance amplifier with an external reference voltage using a comparator.   
     
     
         10 . The biosensor as recited in  claim 9 , wherein said biosensor pixel further comprises:
 a chopper stabilized preamplifier configured to suppress an offset of said comparator.   
     
     
         11 . The biosensor as recited in  claim 1 , wherein said optical filter comprises a plurality of layers of materials with dissimilar refractive index. 
     
     
         12 . The biosensor as recited in  claim 1 , wherein said optical filter is configured to block an excitation signal to said complementary metal-oxide-semiconductor integrated circuit. 
     
     
         13 . The biosensor as recited in  claim 12 , wherein said excitation signal has a wavelength of 532 nanometers. 
     
     
         14 . The biosensor as recited in  claim 12 , wherein said excitation signal is used to excite fluorescent labels. 
     
     
         15 . A biosensor system, comprising:
 a silicon substrate;   active devices fabricated on said silicon substrate;   a plurality of metal layers stacked on top of said active devices;   a passivation layer covering a top metal layer of said plurality of metal layers in order to protect said plurality of metal layers, wherein said passivation layer comprises an opening configured to expose said top metal layer, wherein said opening is used as a sensing electrode; and   a plurality of probes attached to said sensing electrode.   
     
     
         16 . The biosensor system as recited in  claim 15 , wherein said sensing electrode is placed in a solution containing analytes. 
     
     
         17 . The biosensor system as recited in  claim 16  further comprising:
 an interface between said sensing electrode and an electrolyte, wherein an impedance of said interface is changed when an analyte of interest binds to one of said plurality of probes.   
     
     
         18 . The biosensor system as recited in  claim 17 , wherein said change in said impedance of said interface is measured using an electronic sensor. 
     
     
         19 . The biosensor system as recited in  claim 17 , wherein said change in said impedance of said interface is measured using an integrated circuit. 
     
     
         20 . The biosensor system as recited in  claim 19 , wherein said impedance is measured by de-coupling an excitation signal into a first and a second path. 
     
     
         21 . The biosensor system as recited in  claim 20 , wherein current traveling through said interface is multiplied prior to traveling through said first and said second path. 
     
     
         22 . The biosensor system as recited in  claim 17  further comprising:
 impedance sensors for sensing said impedance of said interface, wherein said impedance sensors are integrated in an array format.   
     
     
         23 . The biosensor system as recited in  claim 15  further comprising:
 an excitation electrode, wherein said excitation electrode is an Ag/AgCL electrode.   
     
     
         24 . The biosensor system as recited in  claim 23 , wherein an excitation signal is applied to said Ag/AgCL electrode, wherein said excitation signal is generated using a sinusoidal function generator generating sine waves in a frequency range from 0.01 Hertz to 500 Megahertz.