SBIR Phase I: Nanofluidic Reference Electrode with an Invariant Liquid Junction Potential

This Small Business Innovation Research (SBIR) Phase I project will demonstrate the technical feasibility of a nanofluidic flowing liquid junction (NFLJ) reference electrode. These electrodes, because of their low flow and stable potential, can operate for years without human attention. The objective is to develop a reference electrode with an invariant potential, a flow rate of <100 nanoliters per hour, and a reservoir of 5 ml sufficient for 5 years of continuous operation. I. This nanofluidic device will operate at two orders of magnitude lower flow rate than the microfluidic liquid junction reference electrodes currently under development. The reduced size, and extraordinary long lifetimes due to exceedingly small electrolyte consumption, will make possible handheld pH and potentiometric sensors with a combined shelf life and operating life of up to five years without recalibration or refilling. These miniature reference electrodes are being developed for use with existing portable, handheld, commercial instruments. They will find application in laboratory research, environmental monitoring, and detection of chemical and biological agents. Commercially, a pH sensor with an NFLJ reference electrode offers significantly greater measurement precision over a longer time than any other pH sensor on the market. The precision pH sensor market is involved in measurements for regulatory compliance and for matters of process validation. This market segment pays a premium to obtain the most precise pH sensors available for applications that must withstand the scrutiny of Federal, State, and local regulatory agencies. The annual market for precision pH sensors is 200,000 units and $45 million in sales. This market segment will readily respond to any new sensor technology that results in more precise measurements over longer periods. The NFLJ pH sensor has the potential to become the new standard for such precision pH measurement applications. In addition, the new sensor will require less calibration and maintenance, which will significantly lower the cost of ownership and operation.