I should apologize if my question is trivial since I did not find a similar question, I decided to specifically ask mine.
I have a microscopic membrane in my lab, this piece which we call it NMS has a variation of voltage caused by its operation. Similiar to the action potential in neurons of a nervous system. We are trying to build an electronic measurement system, which could capture the variation of voltage in -70mV to -55mV range. We want to have an accuracy of at least 1mV or possibly less in our measurements. Since the only electronic guy, we have access to is a bachelor student, we shall be able to help him, So I have decided to seek a community help.
The current SoC he knows how to program and feels confident with is ESP32. As I searched its datasheet, it has some cool functionality which we might use here, I add them here as a reference:
- 4.1.2 Analog-to-Digital Converter (ADC)
ESP32 integrates 12-bit SAR ADCs and supports measurements on 18 channels (analog-enabled pins). Some of these pins can be used to build a programmable gain amplifier which is used for the measurement of small analog signals. The ULP-coprocessor in ESP32 is also designed to measure the voltages while operating in the sleep mode, which enables low-power consumption. The CPU can be woken up by a threshold setting and/or via other triggers. With the appropriate setting, the ADCs and the amplifier can be configured to measure voltage for a maximum of 18 pins.
- 4.1.3 Ultra-Low-Noise Analog Pre-Amplifier
ESP32 integrates an ultra-low-noise analog pre-amplifier that amplifies the voltage difference between pins SENSOR_VP and SENSOR_VN and outputs the value to the ADC. The amplification ratio is given by the size of a pair of sampling capacitors that are placed off-chip. By using a larger capacitor, the sampling noise is reduced, but the settling time will be increased. The amplification ratio is also limited by the amplifier, which peaks at about 60 dB gain.
- 4.1.4 Hall Sensor
ESP32 integrates a Hall sensor based on an N-carrier resistor. When the chip is in the magnetic field, the Hall sensor develops a small voltage laterally on the resistor, which can be directly measured by the ADC, or amplified by the ultra-low-noise analog pre-amplifier and then measured by the ADC.
So, I am basically looking for design suggestions for mentioned measurements with ESP32 chips. We need some advice for building the measurement probe too, specifically, we need a way of connecting our NMS membrane which is sandwiched between a microscope slide and a cover slip to our measurement system.
Thank you all.