Diode laser electrochemical sensor for detecting chemical and biological analytes

• US 6,277,651 B1
• Filed: 07/09/1998
• Issued: 08/21/2001
• Est. Priority Date: 07/09/1998
• Status: Expired due to Fees

• Current Assignee: Veridian Engineering Incorporated
• Original Assignee: American Research Corporation Of Virginia, Calspan Srl Corporation
• Inventors: Lo, K. Peter, Groger, Howard P., Churchill, Russell J., Coolbaugh, Myron T.
• Primary Examiner(s): Chin, Christopher L.
• Assistant Examiner(s): PHAM, MINH QUAN K
• Application Number:
  US09/111,735
• Time in Patent Office: 1,139 Days
• Field of Search: 257/253, 257/414, 372/44, 372/43, 436/172, 436/164, 436/518, 422/82.05, 422/82.08, 422/82.07, 422/82.09, 422/82.11, 356/318
• US Class Current: 436/518
• CPC Class Codes: G01N 21/39 using tunable lasers

Abstract

The present sensor allows the user of any diode laser structure to be employed to provide sensitive chemical and biological detector. A diode laser electrochemical sensor is described in U.S. Pat. No. 5,591,407 “Laser Diode Sensor”. The present invention surpasses the capabilities of those sensors by measuring changes in the output power, output spectral characteristics or output signal auto-correlation function to detect the presence of chemical or biological films within the sensitive region.

Claims

1. A method for chemical and biological sensing comprising providing a diode laser with a layered semiconducting structure, and a cap layer positioned on the structure, providing a segmented contact electrode on the cap layer, wherein the segmented electrode further comprises a first contact electrode and a second contact electrode separated from each other by a surface-sensitive gap region, wherein a distance between the first electrode and the second electrode is more than 2 microns, but less than 150 microns, bringing a sample into the surface sensitive gap region, and detecting laser optical output by changes input power, output spectral characteristics output signal autocorrelation function depending upon the presence of chemical or biological films within the surface sensitive gap region correlating the changes in output power, output spectral characteristic or output signal autocorrelation function to the absence or presence of the chemical or biological film further comprising providing gap electrode within the gap region between the contact electrodes and pulsing the gap electrodes.

2. The method of claim 1, further comprising providing two gap electrodes with the gap region, where applied potential of one of the gap electrodes is cycled from a starting point of −

0.8 V to a maximum potential of +0.8 V within a time frame and monitoring output of the diode laser just after increasing the potential.

3. The method of claim 2, further comprising subsequently step changing the applied potential of the gap electrodes from +0.8 V to +0.2 V and thereafter which time monitoring an output signal of the diode laser.

4. A method for chemical and biological sensing comprising providing a diode laser with a layered semiconducting structure, and a cap layer positioned on the structure, providing a segmented contact electrode on the cap layer, wherein the segmented electrode further comprises a first contact electrode and a second contact electrode separated from each other by a surface-sensitive gap region, wherein a distance between the first electrode and the second electrode is more than 2 microns, but less than 150 microns, bringing a sample into the surface sensitive gap region, and detecting laser optical output by changes in output power, output spectral characteristics output signal autocorrelation function depending upon the presence of chemical or biological films within the surface sensitive gap region correlating the changes in output, power output spectral characteristic or output signal autocorrelation function to the absence or presence of the chemical or biological film further comprising providing a voltage between the gap electrode and contact electrodes of about +2 V or −

2 V, for organic solutions.

5. The method of claim 4, further comprising applying the potential according to a range of waveforms (step, triangular or sinusoid) and monitoring laser output as a change in at least one of output power, output spectral characteristics and output signal autocorrelation function.