Chemistry: analytical and immunological testing – Optical result – With fluorescence or luminescence
Reexamination Certificate
1999-11-24
2001-12-18
Snay, Jeffrey (Department: 1743)
Chemistry: analytical and immunological testing
Optical result
With fluorescence or luminescence
C422S082070, C422S082080
Reexamination Certificate
active
06331438
ABSTRACT:
FIELD OF THE INVENTION
The field of this invention is thin film electroluminescent device (“TFELD”)—activated optical sensors, probes, and integrated multiprobe and multisensor arrays for detecting and quantifying biological, chemical, and physical analytes.
BACKGROUND OF THE INVENTION
Detection and quantification of analytes are of prime interest in medical, biochemical, analytical chemical, occupational safety, microelectronic, environmental, military, and forensic applications. Optical sensing and probing is an alternative to electrochemical sensors, which consume analytes, have long response times, have limitations for in vivo use, and are susceptible to poisoning by various contaminants. Various studies on optical methods of analyte detection have been reported in which a dye is immobilized in an analyte-permeable layer. In particular, these studies include sensors whose photoluminescence (“PL”) is affected by the analyte. Such affects may include a change in the PL intensity, spectrum, decay time, or polarization.
Commercially available optical sensors typically employ inorganic single crystal III-V compound LEDs as the light source. However, the need to incorporate optical components to convey light to the sensor and to collect the PL for readout increases complexity, size, and costs. Single crystal GaN-based inorganic LEDs also are incompatible with silicon technology, and thus do not permit fabrication of integrated multisensor arrays.
U.S. Pat. No. 5,517,313 relates to an optical sensor using a P-N junction as a light emitting diode. The LED is placed in an indicator layer which is analyte permeable and contains indicator molecules. The presence of analyte alters the amount of light emitted from the indicator molecules. The emitted light is incident upon a photodetector. The amount of current from the photodetector depends upon the incident light, which is used to detect the analyte. U.S. Pat. No. 5,894,351 relates to an optical sensing device which includes a light-emitting P-N junction having a hole in a direction perpendicular to the P-N junction plane. Upon application of an electrical potential across the junction, light is emitted from the junction into the hole. The hole contains an analyte-permeable fluorescent matrix. A photodetector at one end of the hole generates an electrical signal responsive to light emitted by the fluorescent matrix. P-N junction LEDs, however, are typically prepared from materials that are not compatible with existing silicon technologies and thus do not permit fabrication of integrated multisensor arrays. In addition, P-N junction LEDs cannot be made transparent to allow compact and simple sensor devices that utilize “back detection” to collect the PL signal. Further, P-N junction LEDs are fabricated at temperatures that are too high for integration with temperature-sensitive organic and biochemical sensor materials.
Various multicolor thin film electroluminescent (“EL”) devices are known in the art. For, example, U.S. Pat. Nos. 4,356,429, 4,539,507, 4,720,432, 4,769,292, 4,885,211, and 5,703,436 and European Patents 92311760.0 and 93107241.7 relate to organic electroluminescent devices (“OLED”). Thin film electroluminescent devices (“TFELD”), such as the OLEDs mentioned above and in, e.g., U.S. Pat. Nos. 5,352,906, 5,821,690, 5,399,502, and 5,807,627, have been known for use in display applications. However, to date no disclosure exists relating to the use of TFELDs to activate optical sensors or probes, much less any recognition of the surprising advantages which the present inventors have achieved by the use of TFELDs in new optical sensing and probing technologies.
SUMMARY OF THE INVENTION
What is needed are optical sensors, probes, and multisensor arrays capable of monitoring, quantifying, and analyzing analytes in real-time, which are easy to use, have high sensitivity and specificity, and also are inexpensive to the point of being disposable.
The present invention provides optical sensors, probes and integrated multisensor and multiprobe arrays for measuring a diverse range of biological, chemical, and physical analytes. The sensors, probes, and arrays include an analyte-sensitive layer optically coupled to a thin film electroluminescent device. The TFELD may be deposited on one surface of a glass or other suitable transparent substrate. The other surface of the substrate supports a sensor layer such that the sensor layer, e.g., a polymeric matrix containing dye molecules, can be exposed to the analyte. The sensor layer and TFELD are thus in face-to-face configuration on opposite sides of the substrate. The TFELD is connected to a power source to activate electroluminescence (“EL”) from a luminescent thin film layer of the TFELD. This EL excites the sensor layer to provide an optical response. The optical response varies depending upon the presence of an analyte. The response is detected by a photodiode, CCD array, or other suitable photodetector, and analyzed to determine the properties of the analyte.
The invention also provides arrays containing large numbers of sensor pixels and corresponding TFELDs (collectively called “sensor units”) prepared on-chip in microelectronic configurations. The ability to manufacture TFELD-activated optical sensor units of small lateral dimensions via silicon technology provides a special advantage for “lab-on-a-chip” applications of the invention. The TFELD-activated sensor units of the present invention are easily prepared as an array of several thousand devices on a small transparent substrate. Existing technology allows for deposition of sensor units onto a 400×400 mm
2
substrate with a system throughput greater than 10 substrates per hour. The cost of materials is also minute in comparison to Group III-V compound single crystal-activated sensors and the deposition conditions are much more lax. In addition, the sensor units of the invention can also be readily integrated with microdisplay technologies.
Use of TFELDs, such as organic light emitting devices (“OLED”), permits the construction of sensors that utilize back detection of the signal by, for example, employing optically transparent TFELDs. By “back detection” herein we mean that the photodetector is located on the same side of the substrate as the TFELD; the secondary light (PL) emitted by the sensor or probe, which carries the information concerning the analyte, passes through the TFELD. The devices of the invention are preferably fabricated to allow back detection through a transparent light source. This configuration and the face-to-face coupling of EL into the sensor layer and other advantages of the present invention permit small size, ease of manufacture, low cost, and facilitate the fabrication and use of thin-film sensing arrays on-chip in microelectronic configurations.
A specific embodiment of the present invention relates to a miniature solid-state oxygen sensor. The sensor layer may be, e.g., a thin film of tris(4,7-biphenyl-1,10-phenanthroline)Ru(II) chloride (“Ru(dpp)”) immobilized within a porous sol-gel matrix, the photoluminescence (PL) intensity and decay time (“lifetime”) of which are quenched by molecular oxygen. The Ru(dpp) sensor layer may be applied directly onto the back surface of a blue OLED or other TFELD, which provides pulsed or continuous excitation for the Ru(dpp).
Other specific embodiments of the invention relate to optical biosensors which utilize sensing strategies and indicator systems for sensing ionic species, nucleotides, antibodies, enzymes, and other biologically active moieties. These aspects of the invention provide TFELD-activated ion correlation sensors, enzymatic sensors, immunosensors, and molecular beacons, as will be discussed in greater detail hereinbelow.
Specific applications of the invention include, for example, disposable, integrated OLED/probe or sensor dosimeters, small and active enough that a person can wear them and obtain a status reading at any time. Real-time readout obviates the need to send a measuring device to a lab for analysis. If a person is exposed to a
Aylott Jonathan W.
Chen-Esterlit Zoe
Friedl Jon H.
Kopelman Raoul
Savvateev Vadim N.
Dickstein , Shapiro, Morin & Oshinsky, LLP
Iowa State University & Research Foundation, Inc.
Snay Jeffrey
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