CN108802135B

CN108802135B - Liquid viscosity sensor using organic semiconductor as photosensitive material and preparation method thereof

Info

Publication number: CN108802135B
Application number: CN201810767185.7A
Authority: CN
Inventors: 胡来归; 陈国平; 丰瑞; 苏子畅; 易汉秋; 陈成
Original assignee: Fudan University
Current assignee: Fudan University
Priority date: 2018-07-13
Filing date: 2018-07-13
Publication date: 2020-12-22
Anticipated expiration: 2038-07-13
Also published as: CN108802135A

Abstract

The invention belongs to the technical field of sensing detection, and particularly relates to a liquid viscosity sensor taking an organic semiconductor material as a photosensitive material and a preparation method thereof. The viscosity sensor takes an organic semiconductor material as a photosensitive material, the organic semiconductor material separates out charges under illumination, the charges pass through liquid to be detected, and the detection of the viscosity of the liquid is realized according to the condition that the charges pass through the liquid. The structure of the electrode is a two-electrode system or a three-electrode system; the surface of the working electrode is covered with an organic semiconductor layer; a sample storage pool is manufactured on a substrate, and a counter electrode, a working electrode and a reference electrode are included in the sample storage pool. During detection, the working electrode, the counter electrode and the reference electrode are immersed in a sample to be detected, and the wavelength of a light source corresponds to the peak wavelength absorbed by the organic semiconductor material; the light source irradiates the working electrode, and a pulse photoelectric signal can be detected between the counter electrode and the working electrode. The sensor is simple and convenient to prepare, flexible to use and convenient to integrate; the sensor can be produced in large scale and in batch, and the cost of the sensor is reduced.

Description

Liquid viscosity sensor using organic semiconductor as photosensitive material and preparation method thereof

Technical Field

The invention belongs to the technical field of sensor detection, and particularly relates to a sensor for detecting liquid viscosity and a preparation method thereof.

Background

Viscosity refers to the ability of a liquid to resist deformation under shear forces, and is related to the frictional forces generated when two adjacent fluid planes within the liquid move relative to each other. The viscosity has definite significance for quality identification of various lubricating oils and combustion performance of various fuel oils, and has specific requirements on liquid viscosity in sugar industry, honey processing industry and ice cream manufacturing process. Blood viscosity is also a very important indicator in medical clinical tests. The traditional viscosity detection instrument is large in equipment, large in volume measurement, complex to operate, high in requirement on operators, high in price and incapable of being used for one time. Therefore, it is more important to design and develop a new type of fast and convenient viscosity sensor.

Disclosure of Invention

The invention aims to provide a liquid viscosity sensor with excellent performance, simple preparation and convenient use and a preparation method thereof.

The liquid viscosity sensor provided by the invention takes an organic semiconductor as a photosensitive material, the organic semiconductor material generates current carriers under the irradiation of exciting light, and after the current carriers and liquid to be detected act, the liquid viscosity is detected through electrical measurement.

The invention provides a liquid viscosity sensor using an organic semiconductor as a photosensitive material, which structurally comprises: two electrodes: a counter electrode and a working electrode; or three electrodes: a counter electrode, a working electrode and a reference electrode; wherein, the working electrode is made on the substrate; the working electrode and the counter electrode can be in the same plane or perpendicular to each other. The surface of the working electrode is covered with an organic semiconductor material in a manner of spin coating, evaporation or chemical modification and the like; the electrode is not processed, but forms a circuit loop with the working electrode; the reference electrode is used for indicating the potential of the electrode, and the surface of the reference electrode is not treated; the working electrode and the counter electrode may be of the same material or of different materials.

In the invention, the substrate is made of various non-conductive flexible materials, such as silicon, glass and the like.

In the invention, the organic semiconductor material is a material which does not interact (such as dissolution, chemical reaction and the like) with the liquid to be detected under a dark condition so as to ensure the stable performance of the sensor; under the condition of illumination, the slow photohydrolysis reaction can occur at the interface of the liquid. For example, polymer blend membrane PCBM: PCBM, and small molecule blend membrane ZnPc: C₆₀And the like, as well as various elemental organic semiconductor materials.

In the invention, at least one of the electrode materials is an inert electrode, and the two electrodes are conductive materials with larger work function difference.

In the invention, a sample storage pool is prepared on a substrate and is used for containing a sample to be detected, and electrodes (comprising a counter electrode, a working electrode and a reference electrode) are contained in the sample storage pool and are all immersed in liquid to be detected.

When detecting, the sample to be detected is directly contacted with the electrode. The excitation light is used for irradiating the organic semiconductor material, free charges are separated from excitons at the interface of the organic semiconductor material and the liquid, the charges are transferred to trace ions in the liquid to be detected to form current, and the viscosity of the liquid influences the motion condition and the current magnitude of the trace ions, so that the viscosity of the liquid can be detected according to the current.

In the present invention, the wavelength of the excitation light is generally selected in a wavelength band in which the absorption of the organic semiconductor material is high and the absorption of the liquid to be measured is low. Under the excitation of light, the organic semiconductor and the exciton at the interface of the liquid generate charge separation, the charge is transferred to the dissociated ions in the liquid to be detected to form a current loop, and the viscosity of the liquid to be detected is detected by detecting the current of the counter electrode and the working electrode.

The manufacturing method of the viscosity sensor comprises the following steps:

(1) growing electrodes on a substrate (a two-electrode system comprises a working electrode and a counter electrode; a three-electrode system comprises a working electrode, a counter electrode and a reference electrode); the working electrode and the counter electrode can be coplanar or can be vertical to a vertical plane. The reference electrode is used for indicating the potential of the electrode;

(2) growing an organic semiconductor material on the working electrode in a growth mode of spin coating, evaporation and the like;

(3) a sample storage pool is constructed on the substrate and used for containing liquid to be measured. The electrodes are all contained in the sample storage pool, so that the liquid to be detected can be in complete contact with the electrodes;

(4) an excitation light source is mounted above the working electrode for exciting the organic semiconductor material to separate self-generated charges.

The sensor of the invention has simple preparation method, convenient and flexible use and convenient integration; and mass production can be realized in a large scale, and the cost of the sensor is reduced.

Drawings

Fig. 1 is a schematic diagram of a viscosity sensor based on an organic semiconductor material as a sensitive material.

FIG. 2 is a schematic representation of the experimental set-up of the present invention.

FIG. 3 is a current curve of a working electrode during measurement using an aqueous solution of glucose as a solution to be measured.

Fig. 4 is a schematic diagram of the device operating mechanism.

FIG. 5 is the reciprocal relationship between the photocurrent of the device and the viscosity of the liquid to be measured.

Reference numbers in the figures: 1 is a sample storage pool, 2 is an organic semiconductor material, 3 is a working electrode, 4 is a substrate, and 5 is a counter electrode.

Detailed Description

The following detailed description will be provided to the principles and processes of the viscosity sensor according to the present invention with reference to the accompanying drawings, and the measurement results thereof will be shown so as to be understood and appreciated by those skilled in the art. The present invention will be further described with reference to the embodiments, but the present invention is not limited to the embodiments.

Example 1, a novel solution viscosity photoelectric sensor based on a coplanar electrode structure, as shown in fig. 1, comprises a substrate, a counter electrode, an organic semiconductor film and a sample reservoir. The experimental setup is shown in fig. 2 and comprises a light source, a measurement device and an external circuit.

The organic semiconductor film is formed by using a mixture of P3HT: the PCBM blend membrane is prepared by adopting chlorobenzene as a solvent to be fully mixed with purchased P3HT and PCBM powder (the optimal concentration ratio is 1: 0.8), and the mixture is placed into an ultrasonic cleaning instrument to be oscillated to fully dissolve the powder. The P3HT: PCBM blend membrane is attached to the working electrode (gold) by means of spin coating.

In this embodiment, an aqueous solution of glucose is used as a solution to be measured, and during measurement, positive and negative probes of an ammeter are respectively connected to two electrodes (gold and aluminum or ITO). And starting a laser light source, and performing pulse modulation, wherein the light source is opposite to the working electrode. The current response curve is shown in fig. 3.

As shown in fig. 4. Since P3HT: the absence of sufficient carriers within the PCBM mixed film (organic semiconductor layer) to neutralize ions adsorbed on the semiconductor surface in the absence of illumination, in addition to the water induced bending bands, there may be a built-in electric field in the mixed film caused by the electrode potential difference. After illumination, the photo-generated holes will be collected by the gold electrode, allowing the inhibition of the reaction process that may generate oxygen at the liquid interface, although the Highest Occupied Molecular Orbital (HOMO) level of PCBM is more reactive than the oxygen-resolving potential. Potential ratio of Lowest Unoccupied Molecular Orbital (LUMO) due to P3HT and PCBM 2H⁺/H₂Is lower so electrons are transferred mainly at the hydrogen evolving semiconductor/solution interface. Although in non-electrolyte solution, the slow hydrolysis reaction at the interface generates a small amount of ions to improve the conductivity of the solution, and the solution forms a loop together with an external circuit to form photocurrent.

In this embodiment, the volume and shape of the solution are kept constant, so the length and cross-sectional area of the conductor are also constant, and further, the equivalent steady-state photocurrent of the whole system can be calculated to be proportional to the conductivity of the solution. And the conductivity is inversely proportional to the viscosity, so that the reciprocal of the viscosity of the glucose solution and the photocurrent response (shown in figure 5) can be compared to show good linearity. The novel solution viscosity photoelectric sensor based on the coplanar electrode structure can obtain the viscosity of the solution by detecting photoelectric signals.

Claims

1. A liquid viscosity sensor based on a photosensitive material, the structure comprising: a substrate, a sample storage pool; two electrodes: a counter electrode and a working electrode; or three electrodes: a counter electrode, a working electrode and a reference electrode; wherein, the working electrode is made on the substrate; the working electrode and the counter electrode are in the same plane or are mutually vertical; the surface of the working electrode is covered with a photosensitive material, and an excitation light source is arranged above the working electrode and used for exciting the photosensitive material to separate self-generated charges; the counter electrode and the working electrode form a circuit loop; the reference electrode is used for indicating the potential of the electrode; wherein:

the sample storage pool is prepared on the substrate and is used for containing a sample to be detected, and the electrodes are contained in the sample storage pool and are all immersed in the liquid to be detected;

the photosensitive material does not interact with the liquid to be detected under a dark condition and can perform slow light hydrolysis reaction with a liquid interface under a light condition; comprises a polymer blend film P3HT PCBM.

2. The liquid viscosity sensor of claim 1, wherein the substrate material is a non-conductive flexible material.

3. The liquid viscosity sensor of claim 1, wherein the electrode material is at least one inert electrode and both electrodes are conductive materials with a large work function difference.

4. A method of manufacturing a liquid viscosity sensor according to any one of claims 1 to 3, comprising the steps of:

(1) growing an electrode on a substrate: the two-electrode system comprises a working electrode and a counter electrode; the three-electrode system comprises a working electrode, a counter electrode and a reference electrode; the working electrode and the counter electrode are coplanar or stand on a vertical plane;

(2) growing a photosensitive material on the working electrode;

(3) constructing a sample storage pool on the substrate, and enabling all electrodes to be contained in the sample storage pool;

(4) an excitation light source is mounted above the working electrode for exciting the photosensitive material to separate self-generated charges.