CN101710006B - Three-dimensional micro-force measuring device - Google Patents

Abstract

The invention relates to a three-dimensional micro-force measuring device, which comprises a shock absorption platform 3, wherein an electric control three-dimensional displacement platform 1 and an object stage 2 are fixed on the shock absorption platform 3; a piezoelectric ceramic displacement platform 4 is fixed on a Z axis of the electric control three-dimensional displacement platform 1; a silicon micro three-dimensional micro-force sensor 6 is fixed on the piezoelectric ceramic displacement platform 4; a Wheatstone bridge 12 of the silicon micro three-dimensional micro-force sensor 6 outputs a voltage signal to an amplification operational circuit 13; and the voltage signal is amplified by the amplification operational circuit 13 and then is input in a digital display module 14. The three-dimensional micro-force measuring device can simultaneously measure muN level three-dimensional micro-force, and has the characteristics of high accuracy, high flexibility and good linearity.

Description

A three-dimensional micro-force measuring device

technical field

The invention belongs to the technical field of micro-force testing, and in particular relates to a three-dimensional micro-force measuring device based on a piezoresistive effect-based three-dimensional micro-force silicon microprobe sensor.

Background technique

In recent years, with the continuous development of microelectromechanical systems (MEMS) technology, more and more scholars and research institutions have begun to conduct in-depth research on the microcosm. In order to better manipulate microscopic substances and study their mechanical properties, it is very necessary to carry out research on three-dimensional micro-force measurement technology, especially micro-Newton (uN) level three-dimensional micro-force measurement and sensing technology. The research on the mechanical properties of micro-scale components in MEMS systems, the measurement and loading of micro-forces in robot tactile systems, the micro-force monitoring in the assembly of micro-nano devices, biotechnology, cell manipulation, and micro-manufacturing technology require the measurement and measurement of three-dimensional micro-forces. Therefore, the three-dimensional micro-force measurement has attracted extensive attention from all over the world, and has become a research hotspot at home and abroad. But at present, most of the traditional three-dimensional force measurement systems are still limited to the Newton level, lacking the ability to measure μN-level force; and there are relatively few micro-force measurement systems based on MEMS microsensors, and although they can reach The ability to measure force on the order of μN, but often only one-dimensional or two-dimensional micro force can be measured.

Contents of the invention

In order to overcome the defects of the above-mentioned prior art, the object of the present invention is to propose a three-dimensional micro-force measuring device based on the piezoresistive effect of a three-dimensional micro-force silicon microprobe sensor, which can simultaneously measure the three-dimensional micro-force of μN level, and has high precision and high sensitivity. High, linear features.

In order to achieve the above object, the technical scheme adopted in the present invention is as follows:

A three-dimensional micro-force measuring device, comprising a shock-absorbing platform 3, on which an electronically controlled three-dimensional displacement platform 1 and an object stage 2 are respectively fixed at a certain distance from each other, and a piezoelectric ceramic displacement platform 4 is fixed on the electronically controlled On the Z axis of the three-dimensional displacement platform 1, the silicon micro-three-dimensional micro-force sensor 6 is fixed on the piezoelectric ceramic platform 4; the probe 10 of the silicon-micro three-dimensional micro-force sensor 6 faces downward; the Wheatstone bridge 12 of the silicon micro-three-dimensional micro-force sensor 6 will The voltage signal is output to the amplification operation circuit 13 , and the voltage signal is amplified by the amplification operation circuit 13 and then input to the digital display module 14 .

The electronically controlled three-dimensional micro-displacement platform 1 is composed of a stepping motor controller and an electronically controlled three-axis translation platform of x, y, and z. Its minimum resolution can reach 1.25 μm, and its main function is to roughly adjust the displacement platform. A stepper motor is an actuator that converts electrical pulse signals into angular displacements. When the stepper driver receives a pulse signal, it drives the stepper motor to rotate a fixed angle in the set direction, and its rotation runs step by step at a fixed angle. The angular displacement can be controlled by controlling the number of pulses to drive the guide rail of the electronically controlled translation platform to rotate, so as to achieve the purpose of accurate positioning of the electronically controlled translation platform.

The piezoelectric ceramic displacement platform 4 is composed of a piezoelectric controller and a piezoelectric ceramic precision platform, and the piezoelectric ceramic displacement platform 4 is fixed on the z-axis of the electronically controlled three-dimensional micro displacement platform 1 through a bracket 5 . Based on the inverse piezoelectric effect, by applying a voltage to the piezoelectric ceramics, it deforms in the specified direction to obtain the required micro-displacement. The theoretical resolution can reach 1nm. The main function is to fine-tune the displacement platform.

The main component of the silicon micro three-dimensional micro force sensor 6 is a three-dimensional micro force silicon micro probe sensor based on the piezoresistive effect. When the force in the X, Y or Z direction acts on the sensor, the elastic unit of the sensor is deformed, which causes the deformation of the piezoresistive strip made on the elastic unit, and the resistance changes, which is converted into a voltage through the Wheatstone bridge signal output. The sensor has excellent characteristics such as high sensitivity, high linearity, high resolution, and high stability. It can not only measure three-dimensional force at the same time, but also has a resolution of uN level. It is the core component of the measurement system.

In order to measure the output voltage of the sensor and output accurate measurement values, the signal conditioning and display system is composed of an amplification operation circuit 13 and a digital display module 14 . The amplification operation circuit 13 intends to adopt the instrument amplifier AD620, and the digital display module 14 is composed of a three-and-a-half-digit LED display chip ICL7106 including an A/D conversion module, and displays the micro force value to be measured.

The probe 10 is a quartz fiber probe, and the diameter of the probe tip is less than 60um.

The present invention adopts the method of combining the rough adjustment of the three-dimensional micro-displacement electric control table based on the stepping motor and the fine-tuning of the piezoelectric ceramic micro-displacement table, which well controls the positioning and preload force of the platform, and ensures the measurement range and accuracy; The three-dimensional micro-force silicon microprobe sensor ensures the system's high-precision, high-sensitivity, and high-linear measurement of three-dimensional micro-force; the operational amplifier is used to analyze and amplify the output voltage signal of the sensor, and the measured micro-force is directly displayed through the digital display module. The recording is convenient and simple; therefore, generally speaking, the present invention has good measurement performance, simple operation, and convenient recording, and can be widely used in the measurement of three-dimensional micro-forces in microsystems to promote the improvement of microassembly, micromachining and biological cell technology, and realize microsystem reliable use.

Description of drawings

Fig. 1 is a structural schematic diagram of the three-dimensional micro-force measuring device of the present invention.

Fig. 2 is a structural schematic diagram of the three-dimensional microforce silicon microprobe sensor of the present invention.

Fig. 3 is a circuit diagram of the signal conditioning and display system of the present invention.

Fig. 4 is a schematic diagram of the working principle of the three-dimensional micro-force measuring device of the present invention.

Detailed ways

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

As shown in Fig. 1, the present invention comprises a shock-absorbing platform 3, on the shock-absorbing platform 3, the electronically controlled three-dimensional displacement platform 1 and the stage 2 are respectively fixed at a certain distance, and the piezoelectric ceramic displacement platform 4 is passed through the support 5 Fixed on the Z axis of the electronically controlled three-dimensional displacement platform 1, the silicon micro three-dimensional micro force sensor 6 is fixed on the piezoelectric ceramic platform 4 through the strut 7, and the probe 10 of the silicon micro three-dimensional micro force sensor 6 faces downward.

In the process of force measurement, firstly, the motor controller controls the rotation of the motor 8 in the three directions of X, Y, and Z on the electronically controlled three-dimensional displacement platform 1, and drives the electronically controlled three-dimensional displacement platform 1 to move to perform preliminary inspection on the position of the silicon micro three-dimensional micro force sensor 6. Adjust it so that it is sufficiently close to the object to be measured on the stage 2, and then finely adjust the position of the silicon micro three-dimensional micro force sensor 6 through the controller to control the piezoelectric ceramic platform 4, so that the probe 10 is in contact with the object to be measured. The force measurement is transmitted to the silicon micro three-dimensional micro force sensor 6 through the probe 10, so as to achieve the purpose of force measurement.

As shown in Fig. 2, the silicon micro three-dimensional micro force sensor 6 includes an overload protection unit 11, and an elastic unit 9 is bonded to the overload protection unit 11. Processed by silicon micro-process, four single-ended fixed-supported beams are made of sensitive resistors in the maximum piezoresistive coefficient crystal direction and maximum stress area by ion implantation technology to form a Wheatstone bridge. The sensitive resistors sense the deformation of the beam and convert it into Voltage signal output; in the middle of the mass block of the elastic unit 9, a probe 10 is fixed by an adhesive. The probe 10 is a quartz fiber probe, and the force in the X, Y, and Z directions is transmitted to the elastic unit 9 through the probe. On the cantilever beam, the cantilever beam is deformed. In order to reduce the contact area between the probe and the measured object and improve the sensitivity of the sensor, the probe is corroded with hydrofluoric acid solution so that the diameter of the probe tip is less than 60um; the overload protection unit 11 is a glass substrate, using anodic bonding technology and The elastic units 9 are bonded together, and when the force is too large, the mass block of the sensor is in contact with the glass substrate 11 to prevent the sensor from being damaged. Then, the silicon micro three-dimensional micro force sensor 6 is pasted on the support rod 7 with the needle point facing down, and the other end of the support rod 7 is fixed on the piezoelectric ceramic micro-displacement platform 4 .

FIG. 3 is a signal conditioning circuit of the micro-force measuring device, which mainly includes a Wheatstone bridge 12 , an amplification operation circuit 13 and a digital display module 14 . After the voltage signal is output by the Wheatstone bridge 12, because it is relatively weak, it is amplified by the amplification operation circuit 13 and then input to the digital display module 14, and the micro force value to be measured is displayed through the LED. The amplification operation circuit 13 of the present invention intends to adopt instrument amplifier AD620, and the digital display module 14 is composed of three and a half LED display chips ICL7106 including the A/D conversion module, and displays the micro force value to be measured.

As shown in Figure 4, the present invention writes the displacement control command program through the computer controller, transmits the program command sequence to the three-dimensional displacement platform, and controls the three-dimensional displacement platform to move in three directions according to the displacement scheme set, so that the three-dimensional displacement platform is fixed on the platform. The probe of the silicon micro three-dimensional micro force sensor 6 touches the object to be measured on the stage 2 to apply force to it, which causes the elastic body of the silicon micro three-dimensional micro force sensor 6 to deform, and the sensitive resistance of the sensor changes. The bridge is converted into a voltage signal output, and the voltage signal is displayed through the signal conditioning and display circuit.

Claims (5)

1. three-dimensional micro-force measuring device; Comprise a damped platform (3); Going up apart at damped platform (3), certain position is fixed with automatically controlled three-D displacement platform (1) and objective table (2) respectively; It is characterized in that piezoelectric ceramics displacement platform (4) is fixed on through support (5) on the Z axle of automatically controlled three-D displacement platform (1), and the little three-dimensional micro-force sensor of silicon (6) is fixed on the piezoelectric ceramics platform (4) through pole (7); The Wheatstone bridge (12) of the little three-dimensional micro-force sensor of silicon (6) exports voltage signal to and amplifies computing circuit (13), and voltage signal is input in the digital display module (14) after computing circuit (13) amplifies through amplifying.

2. according to the said three-dimensional micro-force measuring device of claim 1, it is characterized in that the probe (10) of the little three-dimensional micro-force sensor of silicon (6) down.

3. according to the said three-dimensional micro-force measuring device of claim 1, it is characterized in that, amplify computing circuit (13) and intend employing instrument amplifier AD620.

4. according to the said three-dimensional micro-force measuring device of claim 1, it is characterized in that digital display module (14) is made up of the three and half LED display chip ICL7106 that comprised the A/D modular converter.

5. according to the said three-dimensional micro-force measuring device of claim 2, it is characterized in that probe (10) is the silica fibre probe, the probe pinpoint diameter is less than 60um.

Images