JPH08320301A - Concentration distribution-measuring apparatus of a plurality of dissolved substances - Google Patents

Abstract

PURPOSE: To obtain the concentration-distribution measuring apparatus, of a plurality of dissolved substances, by which the distribution in the line direction of the concentration of the plurality of dissolved substances is measured by a single sensor and a single processing part and by which the distribution of the dissolved substances can be output as an image. CONSTITUTION: A sensing part 2 which is composed of a plurality of areas 2a to 2d partitioned respectively in the longitudinal direction so as to respond to different substances is formed on one face of a semiconductor substrate 1, and the semiconductor substrate 1 is irradiated with light L for a probe.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel apparatus capable of obtaining a concentration distribution of a plurality of dissolved substances in a liquid or a solution impregnated in a substance all at once.

[0002]

2. Description of the Related Art Conventionally, as means for measuring the concentration of a dissolved substance in a liquid, there are potentiometric sensors such as glass electrodes and ion selective electrodes, and amperometric sensors such as biosensors.

[0003]

The above-mentioned sensor is characterized by high selectivity. However, when it is desired to measure the concentration of various dissolved species, a plurality of sensors are prepared and the signals from the individual sensors are individually supplied. It requires a complex device that can handle

Further, the measurement by the sensor is premised on that a liquid such as a solution to be measured is sufficiently agitated and the distribution of the dissolved substance is uniform. Therefore, in order to measure the state in which the dissolved substance is unevenly present in the liquid or changes with time in a certain part and capture it as a two-dimensional or three-dimensional image, the sensors are arrayed or the sensor itself is used. Need to be scanned.

However, arraying the sensors requires miniaturization of the sensors and a complicated device having as many input channels as the number of the sensors and capable of processing the obtained signals. Further, when the sensor itself is scanned, “measurement” and “movement of the sensor” are repeated, but most of the concentration distribution of the dissolved substance in the liquid changes rapidly with time, and “measurement” and “sensor The repetition of "movement" does not follow the rate of change. In any case, it is difficult to devise the existing sensor alone, and a technological breakthrough is required.

The present invention has been made in consideration of the above matters, and the distribution of the concentrations of a plurality of dissolved substances in the direction of a line is measured by a single sensor and a single processing part, and the distribution of the dissolved substances is measured. It is an object of the present invention to provide a concentration distribution measuring device for a plurality of dissolved substances, which is capable of outputting as an image.

[0007]

In order to achieve the above object, a concentration distribution measuring apparatus for a plurality of dissolved substances according to the present invention comprises:
A sensing unit consisting of a plurality of vertically partitioned areas is formed on one surface of the semiconductor substrate so as to respond to different substances, and the semiconductor substrate is irradiated with probe light. It is characterized by that.

[0008]

In the measurement of the above-mentioned dissolved substance, the two-dimensional distribution of the dissolved substance can be measured, and LAPS (Light-Addressa) can be measured.
ble Potenteometric Senso
r) An electrochemical image measuring device including a sensor is used. Such a device is disclosed, for example, in Jpn. J. Appl. Ph
ys. Vol. 33 (1994) ppL394-L39
As described in 7, the measurement can be performed by scanning the back surface of the sensing portion with light and extracting the photocurrent induced in the semiconductor by this scanning.

The concentration distribution of the dissolved substance is measured by inserting or contacting the sensing plate of the above device with the substance to be directly measured. The obtained data is output as a two-dimensional or three-dimensional density distribution image by computer processing. Not only the concentration distribution at a certain time,
The state of the change can be tracked in real time.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the drawings. 1 and 2 schematically show an example of an optical scanning type sensing plate SP which is a main part of a concentration distribution measuring apparatus for a plurality of dissolved substances according to the present invention. In FIG. 1, 1 is a semiconductor made of Si. With the substrate, this Si substrate 1
The sensing unit 2 is formed on one surface, and the light irradiation unit 3 that sequentially irradiates the probe light L in the X and Y directions (see FIG. 2) on the back surface of the sensing unit 2 is formed on the other surface. ing.

The sensing section 2 is formed by sequentially forming a SiO ₂ layer 4 and a Si ₃ N ₄ layer 5 on the upper surface of the Si substrate 1 by a method such as thermal oxidation or CVD. The upper surface of the sensing unit 2 is divided into a plurality of areas 2a, 2b, 2c, 2d in the vertical direction (Y direction in FIG. 2), of which the areas 2a, 2b, 2c are measurement areas, For example, area 2a is unmodified to respond to pH, area 2b is modified with a calcium salt of a dialkyl phosphate to respond to Ca ions, and area 2c is
Is modified with a crown ether to respond to Na ions. The area 2d is the measurement area 2a.
To 2c, which functions as a reference electrode section commonly provided, the same structure as the reference electrode disclosed in Japanese Utility Model Publication No. 4-16216 can be adopted.

Each of the areas 2a to 2d forming the sensing section 2 has a width (dimension in the X direction in FIG. 2) of 0.1.
~ 0.5mm, length (Y direction in Figure 2) is 1 ~ 10m
m. CE and RE are counter electrodes and reference electrodes provided above the sensing unit 2, and are connected to a potentiostat 11 described later. OC is the Si substrate 1
This is an ohmic electrode for signal extraction provided at, and is connected to the potentiostat 11.

As shown in FIG. 2, the light irradiator 3 has a light-emitting body substrate 7 on which a plurality of LEDs 6 are formed at equal intervals in the X and Y directions, and the light-emitting body substrate 7.
And a printed circuit board 9 as a scanning control unit having shift registers 8X and 8Y for controlling the LEDs 6 to be sequentially turned on.

Although the sensing part 2 and the light irradiation part 3 are formed separately, the surface of the Si substrate 1 opposite to the sensing part 2 is formed by using an appropriate adhesive or by anodic bonding or direct bonding. And the light-emitting substrate 7 are directly contacted with each other, thereby forming an optical scanning type sensing plate SP having a composite structure (hybrid structure). The optical scanning type sensing plate SP is formed in a watertight structure.

In FIG. 1, 10 is a control device for the optical scanning type sensing plate SP, which is a potentiostat 11 for applying an appropriate bias voltage to the Si substrate 1, and an ohmic contact formed on the Si substrate 1. A current for converting the current extracted from the electrode OC into a voltage signal −
From the voltage converter 12, the lock-in amplifier 13 to which the signal from the current-voltage converter 12 is input, the interface board 14 that transmits / receives a signal to / from the lock-in amplifier 13, and outputs a control signal to the light irradiation unit 3. Becomes
The sensing plate SP is connected by a transmission cable (not shown). Reference numeral 15 is a microcomputer (CPU) as a control / arithmetic unit, 15a is an input unit such as a keyboard, and 15b is a display output unit such as a CRT.

In order to measure the concentration distribution of a dissolved substance in an aqueous solution, in this case, pH, Na, and Ca, using the measuring device having the above-mentioned configuration, the optical scanning type sensing plate SP in FIG. In the direction of arrow Y, dip it in an aqueous solution together with the counter electrode CE. Then, a voltage from the potentiostat 11 is applied between the counter electrode CE and the ohmic electrode OC so that a depletion layer is generated in the Si substrate 1,
A predetermined bias voltage is applied to the substrate 1. In this state, the AC light current is generated in the Si substrate 1 by irradiating the Si substrate 1 with the probe light L for the sensing unit 2 intermittently at a constant cycle (for example, 10 kHz).

The photoelectric flow rate is a value that reflects the pH and the concentration of Na ions and Ca ions of the aqueous solution in contact with the measurement areas 2a to 2c of the sensing unit 2 at a point facing the irradiation point of the Si substrate 1, By measuring these values, it becomes possible to know the pH of the aqueous solution and the Na ion and Ca ion concentrations.

Further, the probe light L is scanned in the X and Y directions by causing the LEDs 6 to sequentially emit light, and the position signals (X, Y) in the measurement areas 2a to 2c and the AC photocurrent value observed at that location are used. , P, as shown in FIG.
It is possible to obtain a two-dimensional image showing the concentrations of H, Ca, and Na. That is, the concentration distributions of a plurality of components can be obtained at the same time, and these can be displayed at the same time.

FIG. 4 shows another embodiment of the present invention. In the measuring apparatus of this embodiment, the measuring areas 2a to 2c and the comparison area 2d are individually provided on the glass substrate 16 as the sensing section 2. This is joined to the light irradiation part 3 to form a light scanning type sensing plate SP having a hybrid structure. Since the operation of this embodiment is the same as that of the above-mentioned embodiment, its details are omitted.

Although the above-described embodiments are all optical scanning type pH imagers having a hybrid structure, the present invention is not limited to this, and an integrated structure (monolithic structure) is provided.
It can also be configured to.

Further, in the above-described embodiment, the probe light L is emitted from the back surface side of the Si substrate 1, but instead of this, it may be emitted from the sensing portion 2 side.

The number of measurement areas is arbitrary, and by appropriately selecting the responsive substance that modifies the surface,
It goes without saying that the distribution of any dissolved substance can be measured.

Further, not only the liquid such as the above-mentioned solution but also the concentration of each dissolved substance such as pH in the soil can be measured as the object to be measured. In that case, it is necessary to appropriately moisten the soil into which the optical scanning sensing plate SP is inserted together with the counter electrode CE and the reference electrode RE.

In any of the above embodiments,
Although the reference electrode RE can be omitted, when the reference electrode RE is provided, a predetermined bias voltage can be applied to the Si substrate 1 more stably.

[0025]

As described above, according to the measuring apparatus of the present invention, the vertical distribution of the concentrations of a plurality of dissolved substances can be simultaneously measured by one sensor and one processing section, and the distribution thereof can be measured. Can be simultaneously output as an image. Then, not only the concentration distribution at a certain time but also the temporal change of the concentration distribution can be tracked.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing an example of a measuring device of the present invention.

FIG. 2 is a plan view schematically showing a configuration example of a light irradiation section of the measuring device.

FIG. 3 is a diagram showing an example of a dissolved substance distribution image obtained by the measuring device.

FIG. 4 is a diagram schematically showing another example of the measuring apparatus of the present invention.

[Explanation of symbols]

1 ... Semiconductor substrate, 2 ... Sensing part, 2a-2d ... Area, L ... Light for probe.

Claims (1)

[Claims] 1. A semiconductor substrate is provided with a sensing portion composed of a plurality of areas divided in the vertical direction so as to respond to different substances, and the semiconductor substrate is irradiated with probe light. An apparatus for measuring concentration distribution of a plurality of dissolved substances, characterized in that