I need help in developing a practical, working design concept for a usb probe to measure liquid concentration. This device will have to be able to plug into a usb port and transmit data that will yield the density of a liquid (like a hydrometer or refractometer). I the most practical and least expensive way to achieve this. I am not looking for a prototype or any type of programming at this time. I am looking for concepts not actual design at this stage.
Freelancer must be in USA or Canada.