Hi,
i am doing a project in which i am packaging MEMS pressure sensor, the pressure sensor is in wheat stone bridge configuration. i am measuring the bridge voltage which of the order of 1mv.
please guide me how i can do it.
thanks and regards
Post a link to the sensor data sheet. An HX-711 strain gauge amplifier/ADC should work.
its piezoresistor based sensor,,, i have to do its characterization and develop its data sheet
Then you must know already about differential amplifers, ratiometric measurements with ADCs, etc. Why are you posting on this hobby forum?
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no actually i do not know about differential amplifiers, ratiometric measurements with ADCs.
i am new that why
please guide me to correct forum.
You need to fully characterize the device and its electromechanical behavior, before thinking about interfacing and making measurements with it.
Piezoelectric devices generally require special design considerations for use with standard MCUs.
what is this
sorry i am new to data acquisition
MCU=Microcontroller, as in Arduino.
When you are ready to post the characterization and electromechanical details of the device, do so and this discussion could go somewhere.
thank you for your time
so to characterize its electromechanical behavior i need to calibrate the sensor with known pressure. In order to calibrate the sensor i need equipment which precisely measure the milivolts, so that i can relate the pressure step with the change in behavior of the sensor.
i am using NI my daq for data acqusistion but its absolute accuracy is 8.8 milivolts which is a problem as it is than the change in voltage the sensor will exhibit during calibration
So how come you have this project, then? Can't the person who gave you the project help you?
That, surely, is a task for someone who does know already about differential amplifiers, ratiometric measurements with ADCs, etc?
exactly you are right but i guess we can learn new things everyday
I recommend to buy a calibrated, professional quality voltmeter capable of making the measurements you require.
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will it work with MEGA 2560 R3 MCU?
Normally the output of a Wheatstone Bridge sensor configuration is specified as for example mV/V which means mV out for each volt of bridge excitation when full scale pressure is applied. For example my 100 Kpa MEMS pressure sensor might for example have a specification of 2.0 mV/V. Applying 10.0 volt excitation and a known pressure of 100 Kpa my Vout should be right about 20 mV.
Finally I would just consider using as suggested an HX711 module in the i9nterest of making things simple. I would also consider using an ADS1115 since both are inexpensive and readily available.
Ron
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thank you for your valuable insight.
can i use instrumentation amplifier like AD620 A module?
you need DC amplifier, show your circuit
= good choice, connect your sensor in parallel to any ( for beginning ) resistor
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currently i am using NI myDaq of National Instrumentation for sensing output of sensor. So i dont need an external circuit. but problem i am facing is due to the accuracy of NI myDaq.... it is giving fluctuating output as its accuracy is 8.8 mV which is more than what sensor output is around 1 mV.
i need complete help in making an amplifier or off the shelf cheap equipment that can give me this accuracy.
Thank you for taking your time out
Developing a data sheet is not a trivial task. If this is for the real world you normally need some expensive equipment with traceable calibration and appropriate records. If it is for a school project something reasonable close should be supplied. You want to measure 0.001 volt, the arduino is not capable of that accurately and stability without external hardware. To be accurate you need to be at least 1 decade better than what you are measuring so you need a meter that will accurately measure 0.0001 volts. Do you have traceable calibration data on all your measuring devices? Parts of a data sheet is temperature related, do you have an environmental oven. Current is also part of the data sheet, how do you plan on measuring that. What about a pressure calibrator which will give you known accurate pressures to work with? I highly recommend you do some more research and determine what you need to do. Do a design of experiments, this will help. Good Luck!
Yes, absolutely. This is the data sheet for the AD620 family. You may want to take note of: "Table 1. Next Generation Upgrades for AD620" as found in the data sheet. Have to love the programmable gain of these amps. The data sheet includes some nice examples.
Ron
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