What is an opamp that is suitable for designing a sensor?

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A suitable op-amp for designing a pH sensor should have low voltage drop, high input resistance (30-100 MOhm), and low input offset voltage. Key considerations include accuracy requirements, operating conditions, and power source type, such as battery life. The OPA128 electrometer op-amp is recommended for its ability to maintain millivolt levels overnight with proper board layout and input guarding. Resources like Linear Technology and Texas Instruments provide valuable information on op-amps for pH meter applications. Selecting the right op-amp is crucial for effective sensor design.
Minh Thanh
I am finding a dual supply op-amp which has rate of voltage dropping to be low , input resistance is high about 30 -100MOhm and input offset voltage is low. All of them serve me to design a sensor that is pH sensor. Can you give me some your ideas for choosing ? Thank you !
 
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It is difficult to decide without considering several considerations.

What is the accuracy that you need? What conditions will this operate in? What is your power source? Is it a battery? What lifetime do you need?

BoB
 
Search on ph meter opamp

my first hit:
http://www.linear.com/solutions/1191You need high Zin. Search on 'electrometer op amp".
I built an integrator with OPA128 electrometer opamp that'd hold a millivolt overnight with just an off the shelf polypropylene capacitor. You have to follow the datasheet directions for board layout and input guarding , though.

http://www.ti.com/lit/ds/symlink/opa128.pdf

old jim
 
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