Methods and devices for xerogel based sensors

Abstract

Fluorescence based sensing systems and methods that exploit xerogels are provided. Embodiments of the invention encompass a sensing system that includes: an optical excitation source emitting over a first predetermined wavelength range and capable of analog modulation over a predetermined frequency range; a sensor including a gel substrate incorporating within its matrix a receptor for molecular recognition of an analyte and a luminophore for signaling a recognition event relating to the analyte, the luminophore emitting an optical signal over a second predetermined wavelength range; a detection circuit including an optical detector for receiving the optical signal emitted by the luminophore and generating a photocurrent in dependence thereof; an excitation circuit that generates an analog signal for modulating the optical excitation source in dependence upon a digital control; and a read circuit for receiving the photocurrent and generating a digital output.

What is claimed is: 
     
         1 . A method comprising:
 providing an optical excitation source emitting over a first predetermined wavelength range and capable of analog modulation over a predetermined frequency range;   providing a sensor comprising a gel substrate incorporating within its matrix a receptor for molecular recognition of an analyte and a luminophore for signaling a recognition event relating to the analyte, the luminophore emitting an optical signal over a second predetermined wavelength range;   providing a detection circuit comprising an optical detector for receiving the optical signal emitted by the luminophore and generating a photocurrent in dependence thereof;   providing an excitation circuit for generating an analog signal for modulating the optical excitation source in dependence upon a digital control; and   providing a read circuit for receiving the photocurrent and generating a digital output, the digital output generated in dependence upon the phase difference between the received photocurrent and the generated analog signal.   
     
     
         2 . The method according to  claim 1 , wherein
 the excitation circuit and read circuit form predetermined portions of a CMOS integrated circuit.   
     
     
         3 . The method according to  claim 1  further comprising;
 a wavelength filter disposed between the sensor and the recognition circuit, the filter blocking a predetermined portion of the first predetermined wavelength range and passing a predetermined portion of the second predetermined wavelength range. 
 
     
     
         4 . The method according to  claim 1 , wherein
 the receptor and luminophore represent a first analyte sensor of a plurality of analyte sensors;   the detection circuit represents a first detection circuit of a plurality of detection circuits, the number of detection circuits being at least the same or more than the number of analyte sensors; and   the read circuit receives the plurality of photocurrents from the plurality of detection circuits, multiplexes a predetermined portion of each of the plurality of photocurrents, and generates from each a phase difference between the received photocurrent and the generated analog signal.   
     
     
         5 . The method according to  claim 1 , wherein
 the gel is selected from the group comprising xerogels, sol-gels, aerogels, hydrogels, and organogels.   
     
     
         6 . A system comprising:
 an optical excitation source emitting over a first predetermined wavelength range and capable of analog modulation over a predetermined frequency range;   a sensor comprising a gel substrate incorporating within its matrix a receptor for molecular recognition of an analyte and a luminophore for signaling a recognition event relating to the analyte, the luminophore emitting an optical signal over a second predetermined wavelength range;   a detection circuit comprising an optical detector for receiving the optical signal emitted by the luminophore and generating a photocurrent in dependence thereof;   an excitation circuit for generating an analog signal for modulating the optical excitation source in dependence upon a digital control; and   a read circuit for receiving the photocurrent and generating a digital output, the digital output generated in dependence upon the phase difference between the received photocurrent and the generated analog signal.   
     
     
         7 . The system according to  claim 6 , wherein
 the excitation circuit and read circuit form predetermined portions of a CMOS integrated circuit.   
     
     
         8 . The system according to  claim 6  further comprising;
 a wavelength filter disposed between the sensor and the recognition circuit, the filter blocking a predetermined portion of the first predetermined wavelength range and passing a predetermined portion of the second predetermined wavelength range. 
 
     
     
         9 . The system according to  claim 6 , wherein
 the receptor and luminophore represent a first analyte sensor of a plurality of analyte sensors;   the detection circuit represents a first detection circuit of a plurality of detection circuits, the number of detection circuits being at least the same or more than the number of analyte sensors; and   the read circuit receives the plurality of photocurrents from the plurality of detection circuits, multiplexes a predetermined portion of each of the plurality of photocurrents, and generates from each a phase difference between the received photocurrent and the generated analog signal.   
     
     
         10 . The system according to  claim 6 , wherein
 the gel is selected from the group comprising xerogels, sol-gels, aerogels, hydrogels, and organogels.   
     
     
         11 . A circuit comprising:
 an excitation circuit for generating an analog signal for modulating an optical excitation source in dependence upon a digital control; and   a read circuit for receiving a photocurrent and generating a digital output, the digital output generated in dependence upon the phase difference between the received photocurrent and the generated analog signal.   
     
     
         12 . The circuit according to  claim 11 , wherein
 the analog signal is the composition of a plurality of sine waves thereby allowing the phase difference between the received photocurrent and the generated analog signal to be determined concurrently.   
     
     
         13 . The circuit according to  claim 11 , wherein
 the circuit is a silicon CMOS integrated circuit.   
     
     
         14 . The circuit according to  claim 11  further comprising;
 an optical excitation source integrated with the excitation and read circuits emitting over a first predetermined wavelength range and capable of analog modulation over a predetermined frequency range; 
 a sensor integrated with the excitation and read circuits comprising a gel substrate incorporating within its matrix a receptor for molecular recognition of an analyte and a luminophore for signaling a recognition event relating to the analyte, the luminophore emitting an optical signal over a second predetermined wavelength range; and 
 a detection circuit integrated with the excitation and read circuits comprising an optical detector for receiving the optical signal emitted by the luminophore and generating a photocurrent in dependence thereof. 
 
     
     
         15 . The circuit according to  claim 14 , wherein
 the gel is selected from the group comprising xerogels, sol-gels, aerogels, hydrogels, and organogels.