OPTO CHIP-BASED VISCOMETER

Abstract

An opto chip for detecting a physical parameter of a liquid sample, comprising an optical structure monolithically integrated with a substrate layer and a functional layer, wherein the substrate layer is light-transmissive and configured to have an upper surface for receiving a droplet of the liquid sample and a lower surface bonded to the functional layer; and the functional layer comprises a light-emitting region and a light-detecting region with the light-emitting region being configured to emit measurement light. The light-detecting region is configured to receive reflected light derived from the measurement light and a signal reflecting the change in intensity thereof is converted into a photocurrent signal. A viscometer and detection method operated using the same opto chip technique. The need for complex external optical calibration is thus eliminated, making the viscometer easier to operate and reducing the overall size of the device.

Claims

1. An opto chip for detecting a physical parameter of a liquid sample, comprising an optical structure monolithically integrated with a substrate layer and a functional layer, wherein: the substrate layer is light-transmissive, and is configured to have an upper surface for receiving droplets of the liquid sample and a lower surface bonded to the functional layer; and the functional layer is configured to comprise a light-emitting region and a light-detecting region with the light-emitting region being configured to emit measurement light from an upper surface of the functional layer, and the light-detecting region being configured to receive reflected light derived from the measurement light, wherein a signal of the change in intensity of the reflected light is converted into a photocurrent signal.

2. The opto chip according to claim 1, wherein the opto chip further comprises a support base plate disposed vertically below the functional layer and monolithically integrated with the substrate layer and the functional layer.

3. The opto chip according to claim 1, wherein the light-emitting region is constituted of at least one of a light-emitting diode, a laser diode or a surface-emitting laser; and the light-detecting region is constituted of at least one of a photodiode or a phototransistor.

4. The opto chip according to claim 1, wherein the substrate layer is formed of sapphire or silicon carbide.

5. The opto chip according to claim 1, wherein the light emitting region and the light-detecting region are formed by epitaxial growth on the substrate layer.

6. The opto chip according to claim 1, wherein the substrate layer is sapphire, and the light-emitting region and the light-detecting region are LEDs epitaxially grown on the sapphire substrate layer.

7. The opto chip according to claim 5, wherein the light-emitting region and the light-detecting region are LEDs epitaxially grown simultaneously on the sapphire substrate layer, and processed into two regions by photolithography and/or inductively coupled plasma etching.

8. The opto chip according to claim 1, wherein the physical parameter includes one or more of viscosity, refractive index and resonant frequency.

9. A viscometer, comprising: the opto chip according to claim 1; a vibrator for providing vertical vibration to the opto chip; and a photocurrent signal processing module, which is configured to process the photocurrent signals output from the light-detecting region and calculate the viscosity of a droplet.

10. The viscometer according to claim 9, wherein the photocurrent signal processing module is also configured to process the photocurrent signal output from the light-detecting region and calculate the refractive index and/or the resonant frequency of the droplet.

11. The viscometer of claim 9, wherein the vibrator comprises a signal generator for applying pulse waves to the vibrator.

12. A method for detecting the viscosity of a liquid sample, comprising the steps of: (1) providing a viscometer according to claim 9; (2) dropping the liquid sample to a surface of the opto chip to form a droplet; (3) applying pulse waves to the vibrator to cause the droplet on the opto chip to vibrate vertically; (4) acquiring the photocurrent signals output from the light-detecting region during the attenuation of the vibration amplitude of the droplet; and (5) processing the acquired photocurrent signals and calculating the viscosity of the droplet by using the photocurrent signal processing module.

13. The method for detecting the viscosity of a liquid sample according to claim 12, wherein the volume of the droplet of the liquid sample is 5 ?l-1 ml, preferably 5-50 ?l, and more preferably 5-10 ?l.

14. The method for detecting the viscosity of a liquid sample according to claim 12, wherein the viscosity of the liquid sample ranges from 2 to 40 cp.

15. The method for detecting the viscosity of a liquid sample according to claim 12, wherein in step (3), the frequency of the pulse waves applied to the vibrator is 10-1000 mHz; preferably, the voltage amplitude of the pulse waves applied to the vibrator is 0.1-10V; and preferably, the duty cycle of the pulse waves applied to the vibrator is 0.01%-1%.

16. A method for detecting the refractive index of a liquid sample, comprising the steps of: (1) providing a viscometer according to claim 9; (2) dropping the liquid sample to a surface of the opto chip to form a droplet; (3) applying pulse waves to the vibrator to cause the droplet on the opto chip to vibrate vertically; (4) acquiring the photocurrent signals output from the light-detecting region during the attenuation of the vibration amplitude of the droplet; and (5) analyzing the acquired photocurrent signals, and calculating the refractive index of the liquid sample from the photocurrent intensity according to Snell's law.

17. A method for detecting the resonant frequency of a liquid sample, comprising the steps of: (1) providing a viscometer according to claim 9; (2) dropping the liquid sample to a surface of the opto chip to form a droplet; (3) applying pulse waves to the vibrator causing the droplet on the opto chip to vibrate vertically; (4) acquiring the photocurrent signals output from the light-detecting region during the attenuation of the vibration amplitude of the droplet; and (5) subjecting the acquired photocurrent signals to fast Fourier transform to obtain the resonant frequency of the droplets.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The embodiments of the present invention are described in detail with reference to the accompanying drawings, wherein:

[0054] FIG. 1 is a schematic diagram of the longitudinal cross-sectional structure of the opto chip of the present invention;

[0055] FIG. 2 is a schematic diagram of the optical mechanism in the opto chip of the present invention;

[0056] FIG. 3 is a photo of the opto chip prepared in Example 1 of the present invention;

[0057] FIG. 4 is a schematic block diagram of the detection system of the present invention constructed in Example 2;

[0058] FIG. 5 shows snapshots taken by a high-speed camera showing the vibration motion of the droplet at (1) the highest point, (2) the normal point and (3) the lowest point in Example 3 of the present invention;

[0059] FIG. 6 is a time domain diagram of the photocurrent signals acquired in Example 3 of the present invention;

[0060] FIG. 7 is a spectrum diagram obtained by subjecting the time domain photocurrent signal shown in FIG. 6 to Fourier transforming as described in in Example 3 of the present invention;

[0061] FIG. 8 is a data plot summarizing the viscosity, refractive index and resonance frequency measured using liquid samples of different viscosities; and

[0062] FIG. 9 is a schematic diagram of the process steps of the chip manufacturing process used in Example 1 of the present invention.

DETAILED DESCRIPTIONS OF EMBODIMENTS OF THE INVENTION

[0063] The present invention will be described in further detail below in conjunction with specific embodiments. The examples given are only for illustrating the present invention, and are not intended to limit the scope of the present invention.

Example 1

Manufacture of Opto Chips

[0064] Referring to the detailed steps as shown in FIG. 9, the optoelectronic chips are manufactured through wafer-level micro-nano processing technology as described below: [0065] (1) an undoped gallium nitride and N-type gallium nitride layer 21, a quantum well layer 31 and a P-type gallium nitride layer 41 were sequentially deposited on a substrate layer 11 by chemical vapor deposition of metal organic compound; [0066] (2) a light-emitting region and a light-detecting region were formed by photolithography and inductively coupled plasma etching, and then a layer of tin-doped indium oxide 51 was deposited; [0067] (3) an electrode layer 61 was deposited by electron beam evaporation; [0068] (4) a Bragg emitting layer 71 was formed by chemical vapor deposition; [0069] (5) the electrode layer was exposed by photolithography and inductive plasma etching; and [0070] (6) the electrode layer material deposition was continued through electron beam evaporation, with the process being controlled to allow the electrode layer to build up beyond the uppermost surface layer, thus ensuring that the electrodes were sufficiently protruding from the outer layer.

[0071] A photograph of the opto chip produced in this example is as shown in FIG. 3, and its plane size is 1?1 mm.

Example 2

Construction of the Detection System

[0072] A detection system of the present invention was constructed as shown in FIG. 4.

[0073] The opto chip made in Example 1 was supplied with current from a power supply 100 in order to cause the LED 121 to emit light steadily. The vibrator 114 was given a pulse wave by a signal generator 112. The vibrator vibrated at a given frequency, causing the optoelectronic chip on the vibrator together with the droplet on the optoelectronic chip 120 to vibrate. The light emitted from the LED 121 was detected by the PD 122, and the received photocurrent signals were amplified by a signal amplifier 116 and then acquired by an oscilloscope 118. Finally, the acquired signals were analyzed by a computer 130 to obtain the relevant properties of the droplet.

Example 3

Detection of Viscosity, Refractive Index and Resonance Frequency

[0074] (1) standard solutions of different viscosities were prepared using glycerol and pure water at 25? C.: 1 cp, 2 cp, 4 cp, 6.2 cp, 7.9 cp, 9.8 cp, 12 cp, 14.2 cp, 16 cp, 17.8 cp, 20 cp, 25 cp, 30 cp and 35.4 cp; [0075] (2) the detection system constructed in Example 2 was connected, and the power supply 100 was set to 10 mA constant current; [0076] (3) 6 ?l standard solution was aspirated by a micro-sampler; [0077] (4) the liquid was dropped onto the center of the opto chip 120; [0078] (5) the vibrator 114 was given a pulse wave with a voltage amplitude of 1V, a frequency of 0.1 Hz and a duty cycle of 0.1%; [0079] (6) oscilloscope 118 signals were acquired, and the data was processed to obtain the relevant properties of the liquid; and [0080] (7) steps (3)-(6) were repeated until all the data to be detected had been obtained.

Characterization and Analysis

[0081] For the detection process of Example 3, the following actions were performed. [0082] (1) For a liquid sample with a viscosity of 2 cp, during the droplet vibration process in step (5) of Example 3, a high-speed camera was used to take photographs of the droplet, as shown in FIG. 5, where: (1) shows the droplet at its highest vertical point; (2) shows the droplet at its normal point or stable point; and (3) shows the droplet at its lowest point. [0083] (2) The time domain diagram of the acquired photocurrent signals was plotted as shown in FIG. 6. [0084] (3) The acquired photocurrent signals were subjected to Fast Fourier transform (FFT transform) as shown in FIG. 7. There is a peak around 52 Hz, which is the resonant frequency of the droplet. [0085] (4) The data of viscosity, refractive index and resonance frequency measured using liquid samples of different viscosities were summarized in FIG. 8. It can be seen from FIG. 8 that as the glycerol concentration increases, the viscosity and refractive index gradually increase, resulting in a gradual decrease in the first resonance frequency and photocurrent, but a gradual increase in the attenuation rate.

[0086] The examples provided above are only preferred embodiments of the present invention, and do not impose any limitation on the present invention. Any equivalent modification or replacement to the technical solutions and contents of this invention made by a person skilled in the art, without departing from the spirit of the present invention, shall still be considered as being within the scope of protection of this invention.