Conduino: an affordable and accurate conductivity probe for density measurements in stratified flows
Joint project with Prof. Marco Carminati (Politecnico di Milano)
In stratified flow experiments, conductivity (combined with temperature) is often used to measure density. The probes typically used can provide very fine spatial scales, but can be fragile, expensive to replace, and sensitive to environmental noise. A complementary instrument, comprising a low-cost conductivity probe, would prove valuable in a wide range of applications where resolving extremely small spatial scales is not needed.
We propose using micro-USB cables as the actual conductivity sensors. By removing the metallic shield from a micro-B connector, 5 gold-plated microelectrodes are exposed and available for 2-wire or 4-wire measurements. These have a cell constant ∼550m–1, an intrinsic thermal noise of at most 30 pA Hz–1/2, as well as sub-millisecond time response, making them highly suitable for many stratified flow measurements. In addition, we present the design of a custom electronic board (Arduino-based and Matlab-controlled) for simultaneous acquisition from 4 sensors, with resolution (in conductivity, and resulting density) exceeding the performance of typical existing probes. The cost of components is less than $100 (excluding the cost of a PCB).
The Conduino is described in our paper in Sensors and Actuators B. The Conduino was selected for a keynote presentation at the 2016 Eurosensors Conference, placing it in the top 1% of the contributions at the largest European meeting in the field.
To make your own Conduino, you can get complete drawings, a parts list and software from our repository: https://github.com/feslab/conduino.
If you are interested in a pre-assembled version, please email conduino [at] gmail [dot] com.
For the story behind the Conduino, head over to the UCSB Current.