Please select a DAQ suitable for our research

[yaaan]

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@santo_13  작성:

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@yaaan wrote:

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@santo_13  작성:

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@yaaan wrote:

We are planning to conduct an experiment to collect bioelectric signals from plants. These signals are approximately ±0.2 mV, and we are considering a sampling rate of around 500 Hz. When collecting the electrical signals, we plan to insert electrodes directly into the plants. We would like to know what suitable DAQ equipment is available and what type of DAQ equipment would be best to use.

Thank you for taking the time to help us with this.

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+/-0.2mV is a very small signal typically riddled with noise for more low-cost DAQ. If you can add an amplifier to bring it to the +/-5V range, you've a wider range of options.

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Are you referring to the construction of an additional amplification circuit when you mention adding an amplifier?

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Yes, one can generalize it as signal conditioning, typically it is amplification and may be paired with filtering as well.

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I had a lot of difficulties building the amplification circuit before... Are there any products or modules that I could use?

[Henrik_Volkers]

Maybe test something like this?

http://www.emelectronics.co.uk/ultra-low-level-dc-voltage-amplifiers/dc-nanovolt-amplifier-model-a10...

the DC offset drift is not specified , but if needed you can ask ..., need an gain defining additional resistor ..

they have other LNA

Place the amplifier near the plant, best with stable temperature and power  with batteries!

I have no experience with that thing.

There are more suppliers, maybe  Bob can give some hints from experience.

[LVNinja]

It depends on the nature of your signal. 

What kind of sensor are you working ? Are they susceptible to noise ? 

If you want off the shelf equipment, you need to know more details to spec the right amplifier. 
In your case signal conditioning is the most critical part, to amplify the signal, remove the noise and then digitize. 

[Bob_Schor]

I am fortunate to have electrical engineering colleagues who are familiar with many types of biological signals and measuring techniques.  In my student/post-doc days, I did build (with their help) EMG, EKG, tungsten or platinum micro-electrode, and glass micropipette amplifiers.  You need to ask colleagues who know your particular needs and have experience with similar recording requirements for targeted advice.

Bob Schor

[NIquist]

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@yaaan wrote:

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@NIquist  작성:

I agree with all the comment above.  The DAQ is mostly irrelevant compared to the need for good signal conditioning in this application.

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In the process of plant -> amplification -> DAQ -> data collection, does this mean that the scaling process in the application is more important?

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Scaling is a different thing.  It refers to taking a sensor's output, which may be in volts, current, resistance, etc. and converting that value to the real-world units (pressure, temperature, altitude) you want to record.  Since you are dealing with electrical signals from plants, I'm not sure what units you are trying to measure (intelligence?, political affinity?, hostility to humans?). 🤔

[yaaan]

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@NIquist  작성:

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@yaaan wrote:

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@NIquist  작성:

I agree with all the comment above.  The DAQ is mostly irrelevant compared to the need for good signal conditioning in this application.

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In the process of plant -> amplification -> DAQ -> data collection, does this mean that the scaling process in the application is more important?

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Scaling is a different thing.  It refers to taking a sensor's output, which may be in volts, current, resistance, etc. and converting that value to the real-world units (pressure, temperature, altitude) you want to record.  Since you are dealing with electrical signals from plants, I'm not sure what units you are trying to measure (intelligence?, political affinity?, hostility to humans?). 🤔

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Ah, I think I might have caused some misunderstanding. What we want to measure is the electrical signal response of plants to stress, and I'm curious if the control in the application after going through the process is the more important part.

[yaaan]

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@Bob_Schor  작성:

I am fortunate to have electrical engineering colleagues who are familiar with many types of biological signals and measuring techniques.  In my student/post-doc days, I did build (with their help) EMG, EKG, tungsten or platinum micro-electrode, and glass micropipette amplifiers.  You need to ask colleagues who know your particular needs and have experience with similar recording requirements for targeted advice.

Bob Schor

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Our team doesn't have anyone with expertise in electrical engineering, so we are curious if there is a way to measure from the plant directly to the DAQ without having to separately create or purchase an amplifier.

[yaaan]

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@Henrik_Volkers  작성:

Maybe test something like this?

http://www.emelectronics.co.uk/ultra-low-level-dc-voltage-amplifiers/dc-nanovolt-amplifier-model-a10...

the DC offset drift is not specified , but if needed you can ask ..., need an gain defining additional resistor ..

they have other LNA

Place the amplifier near the plant, best with stable temperature and power  with batteries!

I have no experience with that thing.

There are more suppliers, maybe  Bob can give some hints from experience.

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Thank you for your response! Since the electrical signals from our experiment are DC components, we're not sure if an LNA (Low Noise Amplifier) would work properly. If we were to connect directly from the plant to the DAQ, is there an appropriate product available?

[Henrik_Volkers]

Since it is not so common to measure cell potentials in plants, there are no common solutions.  Do some paper research, how others solved that problem in the past. 

The of the shelf solution, in my eyes is a nanovolt meter.

Pick up the phone and call Keithley (Sorry NI).  

Don't miss to order cables too.

If your group has no experience in that field, and need to build it up, you will do tests on elektrode and cable materials ....    A trustworthy but slow meter would be on my order list.

Oh and Keithley has some good papers on how to measure small voltages (quantities). 

[Henrik_Volkers]

in nV meterering you love to use pure copper.  So EE guys would use pure copper nails hammered into the plant for good contact. ..  

Ups .. we seem to measure great stress,  all contacted trees died.   

SCNR