I am working on a project to measure dust level in stack. My idea is to measure the tribo-electric (static charge produced by friction between the dust particles and a metallic probe) charge on the probe and relate with the dust concentration. I have designed a charge amplifier (basically an integrator) and getting some signal at the output for higher dust concentration. But for lower concentration it is not sensitive. I am not getting any good response for dust level below 200mg/m3. Any one having any suggestion or have same kind of experiance. DO Analog Device have any AFE/IC for this type of application. Thanks in advance.