Chemistry: electrical and wave energy – Apparatus – Electrolytic
Reexamination Certificate
2000-12-29
2004-11-30
Bell, Mark L. (Department: 1755)
Chemistry: electrical and wave energy
Apparatus
Electrolytic
C435S291400, C435S006120, C324S457000, C257S253000
Reexamination Certificate
active
06824660
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a molecular recognition type chemical charge coupled device (CCD) capable of measuring an ultramicro chemical substance with an ultrahigh sensitivity at a molecular level.
In recent years, it has been required that an environmental pollutant such as dioxin or environmental hormone and protein such as a DNA are measured at a ppb (parts per billion) or ppt (parts per tera) level. The environmental pollutant such as dioxin or environmental hormone should be measured by ultrahigh sensitivity analysis because an ultramicro substance is to be measured.
As a method of measuring ultramicro dioxin or environmental hormone, an SAW (surface acoustic wave) device method and a surface plasmon method have been studied. In the former method, an object to be measured is caused to come in contact with a surface elastic wave device and is measured based on a shift of a resonance frequency, which has a very high universality. It is apparent that analysis of 1 ng (nanogram), that is, in order of 1 ppb can be carried out with a frequency shift of 0.1 Hz. The latter method utilizes light transmission from the inside of an optical material to the outside. In any of the methods, the measurement can be carried out with a high sensitivity. However, an expensive device such as an electronic circuit or an optical system is required over the whole measuring system for operating the device.
For example, DNA measurement has been carried out in the following manner. More specifically, sections of approximately 10 mm square are formed on the surface of a slide glass. Hundreds to hundred thousands of fixed regions having a size of 10 &mgr;m
2
including different probe DNAs from each other are arranged two-dimensionally in one section. One section acts as a DNA chip and has a size of 10 cm
2
. A chip surface is immersed in and washed with a solution containing a target DNA previously subjected to a labeling treatment with a fluorescent material, and the target DNA complementary to the probe DNA is hybridized (associated) to remain on a surface. The hybridized DNA chip surface can be measured as a fluorescent image through a fluorescent laser microscope and a CCD camera, and automatic control is carried out by a computer to perform a data processing. There has also been software in which genes to correspond to positions of a light emitting spot are previously registered in the computer, a fluorescent material for emitting green and red lights having a resolution of 1 to 10 &mgr;m is used to detect a feeble fluorescent intensity when forming a labeling piece, and hybridization profiles such as green and red signals or a yellow signal for double light emission can be compared in the same DNA chip.
However, the conventional method of measuring a DNA is based on a fluorescence method. The DNA to be measured is not directly measured. Therefore, there is a problem in that measuring precision basically depends on a conversion ratio. In addition, an expensive large-scale optical system is used. Therefore, there is a problem in that the whole device is expensive and large-sized.
In order to selectively and easily measure the object, a method of detecting a change in an electric potential of a functional substance as an ion selective electrode is the most effective. Examples of a method of directly and selectively measuring the substance to be measured include a mold polymerizing method (a molecular imprinting method). This method is also referred to as the mold polymerizing method in which a polymeric resin (host) and a substance to be measured (guest) are complexed and polymerized, and the guest is then removed to form a mold having a cavity in a portion of the host where the guest was present, and only molecules corresponding to the mold are taken out.
Examples of a method obtained by developing the mold polymerizing method include an interface mold polymerizing method. In the interface mold polymerizing method, a mold is formed on an oily water interface of a heterogeneous system in which a water layer and an oil layer are present together. The reaction to guest molecules does not reach the inside and is restricted to an interface. Therefore, there is an advantage that mass transfer is rapidly carried out and a response speed is higher than that of the ordinary mold polymerizing method.
In an electrochemical method, a change in a contact with environment pollution molecules can be directly taken as a signal. A large number of methods have been developed as a semiconductor sensor. In order to monitor an environmental polluting molecular concentration and to carry out remote sensing, the development of a gene manipulation technique of a microorganism and a useful function material is insufficient. For example, the remote sensing premises the field installation of an electronic device and plural sensing operations are required for real-time measurement.
There is a higher possibility that two-dimensional sensing might consequently obtain a new knowledge than the acquisition of an ultrahigh sensitivity of one sensor. According to simple calculation, it is possible to obtain a two-dimensional image signal including positional information in which face arrangement sensors of 4096, 16384 and 65536 correspond to a sensor in the two-dimensional sensing of 64×64, 128×128, and 256×256.
Furthermore, a technique for measuring bioimaging of molecules and cells has recently been developed remarkably. It is supposed that a device (chemical CCD) for transferring, through a CCD, electrochemical double layer surface charges generated on an interface between the environmental pollutant and the sensor will enable real-time two-dimensional chemical image measurement in the future. For the chemical CCD, it is proposed “Method and Apparatus for Measuring Physical Phenomenon or Chemical Phenomenon” in Japanese Patent Application No. Hei 9-157716 filed dated on May 29, 1997. The same has published as JP-A-10-332423 or EP-A-0881486. The structure and operation principle of the chemical CCD according to the patent application will be described below with reference to
FIGS. 7
to
9
.
In
FIG. 7
, the reference numeral
1
denotes a chemical CCD having the following structure. More specifically, the reference numeral
2
denotes a semiconductor substrate comprising p-type Si (silicon), for example, and has a thickness of approximately 500 &mgr;m. The semiconductor substrate
2
is provided with a channel stopper
3
, a charge supply section
4
, a charge injection adjusting section
5
, a sensing section
6
to be a charge converting section, a barrier section
7
, a charge transfer section
8
, a floating diffusion
9
, a reset gate
10
, a reset drain
11
, and an output transistor
12
having an MOS structure.
A sensor section
13
is formed by each of the charge supply section
4
, the charge injection adjusting section
5
, the sensing section
6
and the barrier section
7
. The sensing section
6
is formed of a potential well constituted to change a depth corresponding to a chemical quantity, which will be described below in detail. Moreover, an output section
14
is formed by each of the floating diffusion
9
, the reset gate
10
, the reset drain
11
and the output transistor
12
.
As shown in
FIG. 8
, the sensor sections
13
are arranged two-dimensionally to form an array. Thus, information on plural points can be fetched at the same time and signals on the points can be processed in order through the charge transfer section
8
and the output section
13
. As shown in
FIG. 8
, the upper surface of the chemical CCD
1
includes a plurality of sensor sections
13
for converting a chemical phenomenon, for example, pH to electric charges, the charge transfer section
8
for transferring the electric charges obtained by the conversion in the sensor sections
13
in a direction of an arrow, and the output section
14
for converting the transferred electric charges into output signals, and the charge transfer section
8
includes a horizontal CCD 8H and a
Bell Mark L.
Brown Jennine M.
Horiba Ltd.
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