CN103411703B - Non-contact-type temperature measurement method based on cadmium telluride quantum dot photoluminescence - Google Patents

Abstract

A non-contact temperature measurement method based on photoluminescence of cadmium telluride quantum dots, composition and installation of the spectral imaging system, synthesis of semiconductor CdTe quantum dots and sample preparation, temperature calibration, in the spectral imaging system, by adjusting the microscope heating stage The set temperature can obtain the peak wavelength, luminous intensity and half-peak width of the known quantum dot spectrum at different temperatures, and obtain the peak wavelength-temperature, luminous intensity-temperature and half-peak width-temperature three major temperature calibration curves; Electrode Joule heat, microfluidic heat transfer and cell body temperature are measured, which solves the problem that the traditional temperature measurement technology is limited by the space scale. The operation is simple and easy, and only needs to accurately locate the temperature measurement position. Temperature, microchannel fluid, and cell body temperature can be measured precisely and conveniently.

Description

A non-contact temperature measurement method based on photoluminescence of cadmium telluride quantum dots

technical field

The invention belongs to the technical field of micro-nano scale temperature measurement, and in particular relates to a non-contact temperature measurement method based on cadmium telluride quantum dot photoluminescence.

Background technique

The research on the temperature characteristics of key parts of integrated circuits in the field of microelectronics research, the temperature measurement of microchannel fluids and living cells in the field of biomedicine are challenging problems encountered by engineers and scientific researchers today. The relationship between the bandgap width of quantum dot materials and carrier recombination with temperature has inspired us another new type of temperature measurement technology. Traditional temperature measuring instruments include various temperature sensors, thermometers, and thermal imaging cameras, etc., all of which have specific application occasions and sensitivity requirements. For the temperature measurement of key parts of integrated circuits in microelectronic devices and the temperature measurement of cell bodies in the biomedical field, traditional temperature measurement instruments cannot meet the requirements at all. It is very necessary to propose a non-contact spectral temperature measurement technology.

Contents of the invention

In order to overcome the shortcomings of the above-mentioned prior art, the object of the present invention is to provide a non-contact temperature measurement method based on cadmium telluride quantum dot photoluminescence, which can realize accurate measurement of micro-nano structure, microfluid and cell body temperature.

In order to achieve the above object, the technical scheme that the present invention takes is:

A non-contact temperature measurement method based on photoluminescence of cadmium telluride quantum dots, comprising the following steps:

The first step is the composition and installation of the spectral imaging system. A microscope heating stage 3 is placed directly above the microscope objective lens 4, and the sample 1 is fixed on the microscope heating stage 3. The real-time temperature of the sample 1 is measured by the thermocouple 2, and the mercury lamp 9 emits The emitted ultraviolet light passes through the excitation light filter 8 to obtain the excitation light 6 with a wavelength of 340-390nm. The excitation light 6 is reflected by the dichroic beam splitter 7 and then focused onto the sample 1 through the microscope objective lens 4. The emitted light 5 of the sample 1 passes through Microscopic objective lens 4 passes through dichroic beam splitter 7 and emission filter 10 sequentially after receiving light, is focused by condenser lens 11 and reflected to image grating spectrometer 13 by plane mirror 12, and image grating spectrometer finally transmits the optical signal to CCD camera 14 for follow-up processing;

The second step is the synthesis of semiconductor cadmium telluride (CdTe) quantum dots and the preparation of sample 1. The synthesis of semiconductor CdTe quantum dots adopts a bottom-up aqueous phase chemical synthesis method, using cadmium acetate hydrate (Cd(CH ₃ COO) ₂ · 2H ₂ O) aqueous solution as cadmium source (Cd ²⁺ ), potassium tellurite (K ₂ TeO ₃ ) aqueous solution as tellurium source (Te ⁴⁺ ), mix each 50ml at a volume ratio of 1:1 and add Thioglycolic acid (TGA) 18ul was used as a stabilizer, and sodium borohydride (NaBH ₄ ) 80mg was added as a reducing agent to finally form a precursor solution. By controlling the condensation and reflux reaction time of the precursor solution for 4 hours, a green CdTe photoluminescence was obtained. Point, the preparation of sample 1, the preparation of sample 1 select glass slide as the substrate material, its surface is cleaned, and organic polymer silica gel material PDMS16 is spin-coated on the surface of transparent rigid substrate 15, and the concentration of 25uL is 0.2mmol/L The CdTe quantum dot colloid solution 19 was added dropwise to the center of the PDMS16 layer, and heated at 80°C for 10 minutes;

The third step is temperature calibration. In the spectral imaging system, the peak wavelength, luminous intensity and half-peak width of the known quantum dot spectrum at different temperatures can be obtained by adjusting the set temperature of the microscope heating stage 3. Gaussian fitting is performed on the photoluminescence spectrum, and the peak wavelength, luminous intensity and half-peak width signal are extracted, and the extracted signal is one-to-one corresponding to the temperature and linearly fitted, and finally the peak wavelength-temperature, luminous intensity-temperature and half-peak Peak width - temperature three major temperature calibration curves;

The fourth step is to measure the Joule heat of the microelectrode, the heat transfer of the microfluid and the temperature of the cell body,

1) The preparation of the microelectrode, using a transparent rigid substrate 15 with an insulating surface as the substrate, cleaning the surface, spin-coating a layer of EPG533 photoresist 17 with a thickness of 300nm to achieve the negative pattern of the microelectrode, and then A layer of aluminum with a thickness of 200nm is sputtered by a sputtering process, and finally the graphic structure of the microelectrode 18 is realized by a Lift-off process, and 10uL of a 0.2mmol/L CdTe quantum dot colloid solution 19 is added dropwise to the middle part of the microelectrode 18 , the two ends of the electrode are electrified to generate Joule heat;

2) The preparation of the micro-channel, using the transparent rigid substrate 15 as the base, spin-coating a layer of organic polymer silica gel material PDMS16 with a thickness of 100um on the surface after cleaning, and realizing the micro-channel structure on the PDMS by soft embossing method , the width of the microchannel structure is 550um, the depth is 50um, and the concentration of 50uL is 0.2mmol/L. The CdTe quantum dot colloid solution 19 is evenly dispersed in the fluid 21 in advance, and the fluid is introduced into the microchannel by injection;

3) The process of engulfing the quantum dots by the cell body, spreading a layer of cell culture medium 22 on the transparent rigid substrate 15, dispersing 150 uL of CdTe quantum dots with a concentration of 0.68 mg/mL into the cell culture medium 22, adding cells 23 After 24 hours of culture, the quantum dots were evenly dispersed in the cell body through the endocytosis of the cells.

The slit width of the image grating spectrometer 13 is 200um.

The exposure time of the CCD camera 14 is 1s.

The temperature measurement object is a micro system, the substrate is transparent, and the temperature measurement range is from room temperature to 300°C.

The invention fully utilizes the temperature sensitivity of the spectral information of the semiconductor quantum dots, and solves the problem that the traditional temperature measurement technology is limited by the space scale. After the quantum dot is heated, the band gap of the material decreases, resulting in a red shift of the emission spectrum, and the heating will lead to the enhancement of the non-radiative recombination of the carriers, resulting in a decrease in the luminous intensity, and the change in the spectrum can be used as a temperature indicator. The operation is simple and easy, only need to accurately locate the temperature measurement position. For scientific research work, such as the temperature of the microelectrode, the temperature of the microchannel fluid and the temperature of the cell body, it can be accurately and conveniently measured.

Description of drawings

Figure 1 is the front view of the spectral detection system.

Figure 2-1 is the top view after spin-coating PDMS on the substrate and dropping CdTe quantum dot colloid solution; Figure 2-2 is the front view after spin-coating PDMS on the substrate and dropping CdTe quantum dot colloid solution.

Figure 3-1 is the top view after spin-coating photoresist on the substrate; Figure 3-2 is the front view after spin-coating photoresist on the substrate; 3-3 is the top view of the electrode after photolithography, sputtering aluminum layer and stripping ; Fig. 3-4 is the front view of the electrode after photolithography, sputtering aluminum layer and stripping; Fig. 3-5 is the top view after adding CdTe quantum dot colloid solution in the center of the electrode; Fig. 3-6 is adding CdTe quantum dot colloid in the center of the electrode Top view after solution.

Figure 4-1 is the top view after spin-coating PDMS on the substrate; Figure 4-2 is the front view after spin-coating PDMS on the substrate; Figure 4-3 is the top view of the microchannel structure after soft embossing; Figure 4-4 is The front view of the micro-channel structure after soft imprinting; Figure 4-5 is the top view of the micro-channel structure after injecting the microfluid dispersed with CdTe quantum dots.

Figure 5-1 is a top view of a layer of cell culture medium containing CdTe quantum dots; Figure 5-2 is a front view of a layer of cell culture medium containing CdTe quantum dots; Figure 5-3 is a cell culture Figure 5-4 is the front view of the cell culture medium after adding the cell culture medium for a period of time.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings.

A non-contact temperature measurement method based on photoluminescence of cadmium telluride quantum dots, comprising the following steps:

The first step is the composition and installation of the spectral imaging system. Referring to Figure 1, a microscope heating stage 3 is placed directly above the microscope objective lens 4, and the sample 1 is fixed on the microscope heating stage 3. The real-time temperature of the sample 1 is measured by a thermocouple 2. The ultraviolet light emitted by the mercury lamp 9 passes through the excitation light filter 8 to obtain the excitation light 6 with a wavelength of 340-390nm. The excitation light 6 is reflected by the dichroic beam splitter 7 and then focused on the sample 1 through the microscope objective lens 4. The emitted light 5 passes through the dichroic beam splitter 7 and the emitted light filter 10 successively after being collected by the microscope objective lens 4, is focused by the condenser lens 11, and is reflected by the plane mirror 12 to the image grating spectrometer 13, and the image grating spectrometer finally converts the optical signal Transmit to CCD camera 14 and do follow-up processing;

The second step is the synthesis of semiconductor cadmium telluride (CdTe) quantum dots and the preparation of sample 1. The synthesis of semiconductor CdTe quantum dots adopts a bottom-up aqueous phase chemical synthesis method, using cadmium acetate hydrate (Cd(CH ₃ COO) ₂ · 2H ₂ O) aqueous solution as cadmium source (Cd ²⁺ ), potassium tellurite (K ₂ TeO ₃ ) aqueous solution as tellurium source (Te ⁴⁺ ), mix each 50ml at a volume ratio of 1:1 and add Thioglycolic acid (TGA) 18ul was used as a stabilizer, and sodium borohydride (NaBH ₄ ) 80mg was added as a reducing agent to finally form a precursor solution. By controlling the condensation and reflux reaction time of the precursor solution for 4 hours, a green CdTe photoluminescence was obtained. Point, the preparation of sample 1, refer to 2-1, Fig. 2-2, the preparation of sample 1 selects the glass slide as the substrate material, its surface is cleaned, and the organic polymer silica gel material is spin-coated on the surface of the transparent rigid substrate 15 For PDMS16, take 25uL of CdTe quantum dot colloid solution 19 with a concentration of 0.2mmol/L and add it dropwise to the center of the PDMS16 layer, and heat at 80°C for 10min;

The third step is temperature calibration. Referring to FIG. 1, in the spectral imaging system, the peak wavelength, luminous intensity and half-peak width of the known quantum dot spectra at different temperatures can be obtained by adjusting the set temperature of the microscope heating stage 3. Gaussian fitting is performed on the photoluminescence spectrum at different temperatures, and the peak wavelength, luminous intensity and half-peak width signal are extracted, and the extracted signal is one-to-one corresponding to the temperature and linearly fitted, and finally the peak wavelength-temperature, luminous intensity is obtained —Temperature and half peak width—temperature three major temperature calibration curves;

The fourth step is to measure the Joule heat of the microelectrode, the heat transfer of the microfluid and the temperature of the cell body,

1) The preparation of the microelectrode, referring to Figure 3-1, Figure 3-2, Figure 3-3, Figure 3-4, Figure 3-5 and Figure 3-6, uses a transparent rigid substrate 15 with insulating surface as the base, Do cleaning treatment on its surface, spin-coat a layer of EPG533 photoresist with a thickness of 300nm 17 photolithography process to realize the negative pattern of the microelectrode, then use a sputtering process to sputter a layer of aluminum with a thickness of 200nm, and finally use Lift-off The process realizes the graphic structure of the microelectrode 18, and 10 uL of the CdTe quantum dot colloid solution 19 with a concentration of 0.2mmol/L is added dropwise to the middle part of the microelectrode 18, and the two ends of the electrode are powered to generate Joule heat;

2) Preparation of micro-channels, referring to Figure 4-1, Figure 4-2, Figure 4-3, Figure 4-4 and Figure 4-5, using a transparent rigid substrate 15 as the base, and spin-coating on the surface after cleaning A layer of organic polymer silica gel material PDMS16 with a thickness of 100um. The microchannel structure is realized on PDMS by soft imprinting. The microchannel structure is 550um wide, 50um deep, and 50uL of CdTe quantum dot colloid solution with a concentration of 0.2mmol/L19 Uniformly disperse in the fluid 21 in advance, and introduce the fluid into the microchannel by injection;

3) The process of engulfing quantum dots by the cell body, referring to Figure 5-1, Figure 5-2, Figure 5-3, and Figure 5-4, spread a layer of cell culture medium 22 on the transparent rigid substrate 15, and add 150uL concentration 0.68 mg/mL CdTe quantum dots were dispersed in the cell culture medium 22, and after adding the cells 23, after 24 hours of cultivation, the quantum dots were uniformly dispersed in the cell body through the endocytosis of the cells.

The slit width of the image grating spectrometer 13 is 200um.

The exposure time of the CCD camera 14 is 1s.

The temperature measurement object is a micro system, the substrate is transparent, and the temperature measurement range is from room temperature to 300°C.

The invention makes full use of the regular change of the photoluminescence spectrum caused by the band gap of the semiconductor quantum dot being affected by temperature, and solves the problem that the traditional temperature measurement technology is limited by the space scale. After the quantum dot is heated, the band gap of the material decreases, resulting in a red shift of the emission spectrum, and the heating will lead to the enhancement of the non-radiative recombination of the carriers, resulting in a decrease in the luminous intensity, and the change in the spectrum can be used as a temperature indicator. The operation is simple and easy, only need to accurately locate the temperature measurement position. For scientific research work, such as the temperature of the microelectrode, the temperature of the microchannel fluid and the temperature of the cell body, it can be accurately and conveniently measured.

Claims (4)

1. based on a contactless temperature-measuring method for cadmium telluride quantum dot photoluminescence, it is characterized in that, comprise the following steps:

The first step, the composition of spectrum imaging system is installed, microscope warm table (3) is mounted with directly over microcobjective (4), sample (1) is fixed on above microscope warm table (3), the real time temperature of sample (1) is recorded by thermopair (2), the ultraviolet light that mercury lamp (9) is launched obtains by excitation light filter (8) exciting light (6) that wavelength is 340 ~ 390nm, exciting light (6) focuses on sample (1) by microcobjective (4) after dichroic beam splitter (7) reflection, the utilizing emitted light (5) of sample (1) is received after light successively through dichroic beam splitter (7) and utilizing emitted light filter (10) through microcobjective (4), image raster spectrometer (13) is reflexed to through plane mirror (12) after being focused on by condenser (11), image raster spectrometer the most at last optical signal transmission does subsequent treatment to CCD camera (14),

Second step, prepared by synthesis and the sample (1) of semiconductor cadmium telluride (CdTe) quantum dot, the synthesis of semiconductor CdTe quantum dot adopts aqueous reaction synthetic method from bottom to top, adopts cadmium acetate hydrate Cd (CH ₃cOO) ₂2H ₂o aqueous solution is as cadmium source Cd ²⁺, potassium tellurite (K ₂teO ₃) aqueous solution is as tellurium source Te ⁴⁺, both add mercaptoacetic acid (TGA) 18ul as stabilizing agent after each 50ml mixing of the volume ratio of 1:1, add sodium borohydride (NaBH ₄) 80mg is as reductive agent, final composition precursor solution, by controlling the condensing reflux reaction time 4h of precursor solution, obtaining photoluminescence is green CdTe quantum, the preparation of sample (1), the preparation of sample (1) selects microslide as backing material, cleaning is done on its surface, at transparent rigid base material (15) surperficial spin coating organic polymer silica gel material PDMS (16), getting 25uL concentration is that the CdTe quantum colloidal solution (19) of 0.2mmol/L drops to PDMS (16) layer central authorities, heats 10min at 80 DEG C;

3rd step, temperature calibration, in spectrum imaging system, the peak wavelength of quantum dot spectrum under known different temperatures, luminous intensity and half-peak breadth can be obtained by regulating the design temperature of microscope warm table (3), photoluminescence spectra under different temperatures is carried out Gauss curve fitting, extract peak wavelength, luminous intensity and half-peak breadth signal, the signal of extraction and temperature one_to_one corresponding are done linear fit, finally obtains the large temperature calibration curve of peak wavelength-temperature, luminous intensity-temperature and half-peak breadth-temperature three;

4th step, measures microelectrode Joule heat, microfluid heat transfer and cell body temperature,

1) preparation of microelectrode, adopt the transparent rigid base material (15) of surface insulation as substrate, cleaning is done on its surface, spin coating a layer thickness is the negative pattern that EPG533 photoresist (17) photoetching process of 300nm realizes microelectrode, sputtering technology is adopted to sputter the aluminium that a layer thickness is 200nm afterwards, the graphic structure of microelectrode (18) is finally realized by Lift-off technique, be that 0.2mmol/L CdTe quantum colloidal solution (19) is added drop-wise to microelectrode (18) middle part by 10uL concentration, electrode two ends power up generation Joule heat;

2) preparation of fluid channel, transparent rigid base material (15) is adopted to be substrate, be the organic polymer silica gel material PDMS (16) of 100um in surperficial spin coating a layer thickness after cleaning, on PDMS, micro-channel structure is realized by soft impression method, the wide 550um of micro-channel structure, dark 50um, 50uL concentration is that 0.2mmol/L CdTe quantum colloidal solution (19) is dispersed in fluid (21) in advance, introduces in fluid channel by injecting method by fluid;

3) cell body engulfs the process of quantum dot, at transparent rigid base material (15) upper tiling one layer of cells nutrient culture media (22), be that the CdTe quantum of 0.68mg/mL is distributed in cell culture medium (22) by 150uL concentration, after adding cell (23), through the cultivation of 24h, make quantum dot dispersed at cell body by the endocytosis of cell.

2. a kind of contactless temperature-measuring method based on cadmium telluride quantum dot photoluminescence according to claim 1, is characterized in that: described image raster spectrometer (13) slit width 200um.

3. a kind of contactless temperature-measuring method based on cadmium telluride quantum dot photoluminescence according to claim 1, is characterized in that: CCD camera (14) time shutter is 1s.

4. a kind of contactless temperature-measuring method based on cadmium telluride quantum dot photoluminescence according to claim 1, it is characterized in that: described thermometric object is microsystem, base material is transparent, and temperature-measuring range is that room temperature is to 300 DEG C.