Radiant energy – Photocells; circuits and apparatus – Housings
Reexamination Certificate
1999-10-12
2001-12-04
Lee, John R. (Department: 2828)
Radiant energy
Photocells; circuits and apparatus
Housings
C250S573000, C422S082050, C436S165000
Reexamination Certificate
active
06326612
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates in general to sensor systems in the fields of chemical, biochemical, biological and biomedical analysis, and more particularly, to a system and method for optical sensing utilizing a portable, detachable sensor cartridge device for permitting qualitative and quantitative analysis about a sample of interest when used in conjunction with a fixed optic sensor.
BACKGROUND OF THE INVENTION
Without limiting the scope of the invention, its background is described in connection with analytical measurements of a wide variety of analytes using a fixed optic sensor employed in sensor systems in the fields of chemical, biochemical, biological and biomedical analysis, such as a surface plasmon resonance sensor, a critical angle sensor, or a fluorescence-based sensor, for example.
Summarized briefly, a surface plasmon is known in the art as a surface charge density wave at the surface of a dielectric interface having a thin conductive film formed thereon. The oscillation of free electrons at a conductor-dielectric boundary is affected by the refractive index of the material adjacent to the film. Using a polarized beam of monochromatic light, surface plasmon polaritons can be excited. Resonance occurs when the polarized light is totally internally reflected from the conductive film. The light internally reflected from the film has a minimum intensity at the resonance angle. By detecting the resonance angle, the refractive index of a material adjacent to the film may be determined, which is indicative of other properties of the material. A more detailed description of surface plasmon resonance may be found in the article “Surface Plasma Oscillations and Their Applications,” Rather, H.,
Physics of Thin Films
, 1977.
Sensoring systems using critical angle measurements are also known in the art. Since critical angle is a mathematical function of refractive index, determination of the critical angle gives rise to the determination of the refractive index of a sample, which is indicative of one or more sample properties, from which further qualitative and quantitative analyses about the sample may be made. In a typical critical angle sensor system, when polarized light rays are directed to a sample of interest at angles of incidence smaller than the critical angle, a portion of the light is refracted into the sample, resulting in an overall loss. At angles of incidence larger than the critical angle, total internal reflection occurs, and the full intensity of the light is reflected off the sample. The critical angle, and consequently the refractive index, may be then determined by measuring the intensities of the reflected light rays, and detecting a transition from a high intensity to a low intensity. A more detailed description of critical angle sensors may be found in U.S. patent application Ser. No. 60/027,286, the contents of which are herein incorporated by reference.
The use of fluorescence based methodologies to detect sample gases and liquids is also known in the prior art. A typical application involves the molecular labeling of a film or other article followed by excitation and fluorescent measurement in the presence of the particular sample of interest. Fluorescent labeling involves the deposit of a suitable fluorescence chemistry known to interact with the sample of interest. A source of excitation light is directed at the coated article, which when brought in contact with the sample, emits a low intensity fluorescence energy. A photodetector may be used to measure the emission and therefore detect the presence of the sample. A more detailed description of fluorescence-based sensors may be found in U.S. patent application Ser. No. 60/027,287, the contents of which are herein incorporated by reference.
SUMMARY OF THE INVENTION
In prior art sensing systems, analytical measurements have been primarily conducted in a centralized testing environment. This generally requires that a sample of interest be brought to a specially equipped lab for analysis. Such a testing environment restricts measurements to those that can tolerate delays effected by, as well as costs imposed by such a methodology. As often is the case with the use of biomedical sensors in medical emergencies, for example, analytical determinations must be immediately made in-situ.
Furthermore, in prior art sensing methodologies, optical connections, fluidic connections and electrical connections to a host unit have been usually made in a series of steps. Typically, a sensor is first plugged into its electrical socket, and subsequently, an inlet tube is inserted into a flow cell. Optical connections are then achieved, and precise optical alignment and calibration are made. Such a methodology is time-consuming and difficult and does not generally allow for analytical measurements to be taken easily, rapidly and accurately at the point of need.
Furthermore, sensors in the prior art have typically utilized metal pins as electrical connectors to a host unit. These pins are typically exposed and are therefore more susceptible to damage such as electrostatic interference or shorting. These unprotected pins are even more susceptible to damage if the sensing device has a slick surface, making it more slippery and therefore more likely to be dropped.
Yet another problem with prior art sensing systems involves the generation of biohazardous waste. The potentially contagious nature of this waste dictates that it be collected efficiently and disposed of properly.
A need has therefore arisen for an efficient, portable, replaceable sensing device that overcomes the disadvantages in the prior art. A sensing device that can perform measurements at the point of need and that simultaneously and rapidly provides for fluidic connections and electrical connections while eliminating the need for separate optical connections would be extremely advantageous over the prior art. A device that is small, portable, and lightweight, and that integrates the electrical and fluidic connectors and the various electro-optical sensing components on a single platform would have widespread application and would fill the void left by prior art sensors. A device that is low-cost, and allows for efficient, high-volume, wafer-scale mass production would be highly desirable as well.
The present invention disclosed herein can comprise an optical sensing system and sensor cartridge for making analytical measurements regarding one or more samples of interest, the cartridge comprising an opaque housing having an opening, the opening allowing access to one or more electrically conductive contacts and one or more fluidic connectors disposed within the housing; a flow cell having one or more channels connected to the one or more fluidic connectors; and a fixed optic sensor disposed within the housing. The fixed optic sensor system may be, for example, a surface plasmon resonance sensor, a critical angle sensor, or a fluorescence-based sensor. In one embodiment of the present invention, the one or more electrically conductive contacts comprise card-edge contacts. In an alternative embodiment of the present invention, the one or more electrically conductive contacts comprise conductive pins intended to be inserted into a socket of a host analytical unit.
Because the optic sensor is pre-aligned, e.g., a sensing surface portion of the optic sensor is mounted on the flow cell, and at least one of the fluid connectors is aligned with the electrical contacts, the cartridge can be easily replaced on a host unit to allow, e.g., field analysis of multiple fluids.
The present invention can provide a sensing device that simultaneously and rapidly provides for both fluidic connections and electrical connections and thus can provide meaningful data to be analyzed and interpreted by a host unit such as a computer or other similar system.
The present invention can also provide a low cost sensor that may be manufactured in high volume. The present invention can be a miniature, lightweight, portable, detachable sensor that uses low-cost com
Carr Richard A.
Elkind Jerome L.
Melendez Jose L.
Brady III W. James
Lee John R.
Telecky , Jr. Frederick J.
Texas Instruments Incorporated
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