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AD5934 for mid-frequency (10 kHz -100 kHz), high impedance (100kOhm+) measurement

Question asked by esotronic on May 10, 2016
Latest reply on May 12, 2016 by Davidforde

I have designed a device for the measurement electrical impedance between microelectrodes (on the order of 4 square microns) for the detection of single bacterial cell.

 

The issue is that my expected solution impedance is on the order of 200-400k Ohms and I need to measure at 10-100 kHz due to electrode polarization (on the order of 2 pF in series with the solution impedance). Parasitics due to cabling, pcbs, muxes, etc. are destroying my measurement. I was hoping that the move to a chip-based MUX might help reduce some parasitics.

 

What parasitics might I expect for the AD5934? I would like to know if there are low-cap muxes that you recommend for these mid-speed, mid-impedance ranges, and if the AD5934 is suitable for these measurements. If not, is there another chip that is suggested for this application?

 

I'm also interested in low-capaictance (<1 pF) multiplexers. Any recommendations?

 

Thanks!

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