Capacitance Sensing

[Bill Kinder]

Hi,

I am doing a master’s project that uses Chi.Bio, and I am working on integrating capacitance sensing into the bioreactor chamber.

My plan is to stick adhesive copper tape on the outer surface of the cylindrical tube, and connect that to an off-the-shelf capacitance-to-digital converter (e.g.: FDC1004 from TI) via coaxial cable, then routing the digital outputs to I2C pins on the Beaglebone.

I will need to modify one of the side plates to accomodate FDC1004 and supporting circuitry, as well as consider electrode geometry, shielding, etc. However the main challenge is I2C connection, since that may require soldering onto the Beaglebone connector pins, which are stuck to the Chi.Bio PCB. I am able to do this but would prefer not just in case I mess up the solder joints.

My application is yeast flocculation sensing. I’m doing an optogenetics experiment where blue light will activate FLO1, the gene encoding flocculation in yeast. Flocculation alters the dielectric properties of the medium, thus can be detected using a simple capacitance sensor – also through optical density / light scattering, but I want to add something new to Chi.Bio.

Any recommendations?

EDIT: I just realised the bioreactor chamber would have I2C pins for communicating with the Beaglebone, right? I could probably use those.

Kind regards,
Bill.

• This topic was modified 2 weeks, 2 days ago by Bill Kinder.

[harrison]

Hey Bill
On the side of the ChiBio there is a white header with I think 6 pins which you have likely looked at but never used. THis is a generic expansion header which includes pinout of I2C. So what I would suggest is go download the circuit schematics available on this site, figure out the pinout there, and connect directly to this. It gives you power too if you want it.

[Bill Kinder]

Thanks Harrison, that’s perfect. I’ll let you know how things go.

[Author]

Posts