Design an Arduino system that measures the temperature difference between two thermistors

Design an Arduino system that measures the temperature difference between two thermistors


Job Description

Design (and optionally ship to Northern California) an Arduino or similar device that meets the following conditions. I will use this with but need help with the EE side of things...

1) Provides two NTC thermistors on 60" leads. We shall call these temperature sensor A and sensor B.
2) Is intended to measure the temperatures within the range 30°C/86°F to 38°C/100.4°F. Please choose the thermistors carefully :)
3) Measures the relative temperature DIFFERENCE between sensor A and sensor B and sends that outputs as a value between 0 to 1023 via the serial port (to be consumed by Quartz Composer per URL above.)
4) The sensitivity can be adjusted from 0.05°C to APPROXIMATELY 5°C using a trimpot. E.g., at the lowest setting, a 0.05ºC or higher difference registers as 1023, while at the highest setting a APPROXIMATELY 5ºC difference is required. What's important is the higher side of the sensitivity sensitivity; I imagine that the used range will almost always be <2°C.
4a) Bonus ($$$) if sensitivity value is also available within Quartz Composer per above with working example (displaying values is fine).
5) Assign all rights to the foregoing design (copyright/patent/etc) to myself and agree to execute a non-disclosure agreement upon commencement of the work.
6) The design can be assembled on a breadboard with readily available parts.
7) If you would like to assemble and ship the item (for an additional fee to be specified by the contractor), package it in a small case that does not need to be opened to adjust the trim pots.
8) Operates off USB power or readily-available batteries, ideally CR2032 or AAA.

Note that sensitivity over accuracy/reproducibility is the goal. It is not important that I can reliably state "Oh, I know the temperature differential is 1°C because I haven't touched the trim pots and it's reporting '504'." Rather, I'm most interested in seeing relative changes in temperature between the two thermistors with the greatest (adjustable) accuracy. I don't need to know what the absolute temperatures are or even the absolute difference... the trimpot is there to calibrate the sensitivity and the difference would be measured over time.

In your bid, please specify a firm estimate for schematics that meet the above description. If you are willing to build and ship it for an additional fee, please advise what that is. You will be well treated! :)

Skills: design