Audio jack based miniaturized mobile phone electrochemical sensing platform

We demonstrated a mobile phone sensing platform, MoboSens, with integrated plug-n-play microelectronic ionic sensor that performs electrochemical measurement by using audio jack of a smartphone. This platform was used to measure nitrate concentration using few microliter liquid samples on field along with providing geospatial map locations through wireless network. This compact MoboSens platform (∼65 g) based on smartphone is able to detect nitrate concentration in water with a limit of detection of 0.2 ppm within 1 min. The nitrate ion detection on MoboSens platform is performed by a microfabricated microfluidic sensor utilizing cyclic voltammetry based electrochemical process. The stability of the measurements was verified by performing the experiments under varying temperature, pH and ion interference conditions. The mobile phone app reports the quantitative nitrate sensing results along with user's input metadata. The results can be automatically saved on secure cloud servers or can be pushed on public social media, e.g. Twitter. Finally, the digital sensing information can be retrieved with geospatial information tagged on an internet map service, e.g. Bing Map for public sharing and viewing. We tested this lab-on-a-chip mobile sensing platform for field water quality measurement and confirmed our mobile sensing results with other existing analytical testing methods.