Op Amp Circuit Noise

[AdamZ]

Very interesting way to create a nanometer sized fluid channel in a silicon nitride thin membrane. I assume you will use the Axopatch 200B to track the DNA strands as they make their way through the hole. Is it your intent to make just one hole per membrane, or is there a goal to make an array of holes?

Unfortunately, I don't think this particular technology is applicable to PCSS fabrication. <sigh>

Thanks for the link to the paper. I've always been fascinated with the electronics aspect of bio-engineering but (so far) have been unable to break into that field, even at the company where I was previously employed, where I thought I might make a contribution. Instead of hiring me, they farmed the work out to a third party to manufacture bio-sensors. Probably a good idea at the time, but I was disappointed. Now I am retired without access to all the fancy toys. I can appreciate the problem of trying to find a nanotube with an electron microscope in such a vast field. Narrowing down the search area with a mask, prior to creating the hole was clever.

Best of luck on getting your instrumentation working. The 1/f noise contribution to the "leakage" current through these holes appears to have an inverse relation to hole diameter. Any ideas on why that occurs? Does it have anything to do with the mean free path of ions in solution that find their way through the nanopore hole?

Thanks a lot. I think 1/f flicker noise is related to direct current, which scales with diameter as follows: I= pi/(4*l)*d^2*sigma, where d is the diameter of the pore, l is the length of the pore, and sigma is the bulk conductivity.

 

[hevans1944]

Your equation describes what the 1/f noise is as a function of pore dimensions and bulk conductivity, but it doesn't explain how this noise originates. 1/f noise has been a bug-a-boo of electronics since before I was born, rearing its ugly head with thermionic electron devices (vacuum tubes) and then again when integrated circuits were being developed. I have never seen a satisfactory explanation for the phenomenon, but plenty of empirical equations describing particular circumstances exist. The latest is this paper, hidden behind a pay-wall, and briefly described here. Anyhoo, my conjecture is 1/f noise in nano-pores is a random ionic collision process that mediates passage of ions in solution through the pore.