FatSeagull
Newbie level 4
Hello. I am a graduate student with background in Biology, and I would like to request a sanity check.
Context:
I am currently working with an organic polymer sample which changes its current response in response to changes in its environment.
Tentative experimental data shows that the polymer's current response seems to be non-ohmic in nature.
Currently, I am using this expensive piece of equipment from Zurich Instruments to measure the current response and the phase response:
However, due to its cost, We only have one of these machines in the lab. This has become a serious bottleneck in the pace data collection.
Furthermore, as one of the applications of my polymer is use in sensors, there is a need for miniaturizing the setup that is required to collect the current response data.
When 1V 200Hz current is ran through the polymer sample, its current response ranges from 100μA to 100pA, depending on the conditions.
This leads me to believe that the polymer behaves mostly as a resistor, with limited capacitance (Since there is a phase response of 6~20 degrees, depending on the surrounding physical conditions).
I wanted to see if miniaturizing the measurement setup was possible. However, the fact that the lab went out of its way to purchase this $10K machine instead of telling someone to DIY it is giving me some pause. After all, if a DIY solution was so easy, then chances are, someone would have done it by now, right?
Assuming that optimizing for performance and size takes precedence over cost:
Questions:
1) Would you recommend/recommend against using something like an Arduino/RPi for collecting the readout data? If not, what other portable, small solutions can you recommend? My biggest concern is that Arduinos usually output DC signals, but the polymer sample exhibits response only with AC stimuli.
2) Would a Transimpedance Amplifier (TIA) Circuit be a good starting point for the actual 'measurement' circuit?
3) Given the very small possible current range, Signal to Noise Ratio is a big concern for me. Would a ultra low bias current op-Amp like LMP7721 be the best for the job? Or are there better options out there?
4) Given the wide range of expected current values, I am unsure if a single Op-Amp is able to handle my requirements, as the bias current range for a single Op-Amp may not be able to handle the range of expected inputs. Is this a valid concern? How would you best address this?
Thank you very much for your help.
Context:
I am currently working with an organic polymer sample which changes its current response in response to changes in its environment.
Tentative experimental data shows that the polymer's current response seems to be non-ohmic in nature.
Currently, I am using this expensive piece of equipment from Zurich Instruments to measure the current response and the phase response:
MFIA 500 kHz / 5 MHz Impedance Analyzer
The Zurich Instruments MFIA is a digital impedance analyzer and precision LCR meter that sets the new standard for impedance measurements in the frequency range
www.zhinst.com
However, due to its cost, We only have one of these machines in the lab. This has become a serious bottleneck in the pace data collection.
Furthermore, as one of the applications of my polymer is use in sensors, there is a need for miniaturizing the setup that is required to collect the current response data.
When 1V 200Hz current is ran through the polymer sample, its current response ranges from 100μA to 100pA, depending on the conditions.
This leads me to believe that the polymer behaves mostly as a resistor, with limited capacitance (Since there is a phase response of 6~20 degrees, depending on the surrounding physical conditions).
I wanted to see if miniaturizing the measurement setup was possible. However, the fact that the lab went out of its way to purchase this $10K machine instead of telling someone to DIY it is giving me some pause. After all, if a DIY solution was so easy, then chances are, someone would have done it by now, right?
Assuming that optimizing for performance and size takes precedence over cost:
Questions:
1) Would you recommend/recommend against using something like an Arduino/RPi for collecting the readout data? If not, what other portable, small solutions can you recommend? My biggest concern is that Arduinos usually output DC signals, but the polymer sample exhibits response only with AC stimuli.
2) Would a Transimpedance Amplifier (TIA) Circuit be a good starting point for the actual 'measurement' circuit?
3) Given the very small possible current range, Signal to Noise Ratio is a big concern for me. Would a ultra low bias current op-Amp like LMP7721 be the best for the job? Or are there better options out there?
4) Given the wide range of expected current values, I am unsure if a single Op-Amp is able to handle my requirements, as the bias current range for a single Op-Amp may not be able to handle the range of expected inputs. Is this a valid concern? How would you best address this?
Thank you very much for your help.
