Porous Titanium Nitride electrodes on miniaturised pH sensor for foetal health monitoring application
Résumé
Measuring pH level on foetal scalp by blood gas
analyser is a common practice to prevent the risk of acidosis in
monitoring foetal health during labour. However, this current
technique of collecting capillary sample is not continuous and
has high rate of failures. In this work, a prototype of
miniaturized pH sensor based on Titanium Nitride (TiN)
electrodes to get continuous measurement of pH targeting foetal
health monitoring has been developed. By exploiting wet etching
techniques on flat TiN electrodes, porosity of the working
surface area has been increased, exhibiting better properties
and performances of our pH sensor. Precision of the developed
TiN pH sensor is 0.02 in pH, which is close to the requirement
of the application. The sensitivity is determined to be
60.24 mV/pH within pH range of interest from 6 to 8. In
addition, the potentiostatic electro impedance spectroscopy
(PEIS) and cyclic voltammetry (CV) were recorded, showing a
7.7-time smaller impedance at 100 Hz frequency and a better
conductivity compared to the flat TiN electrode. This work is
under the next step of fabrication to transfer the system from
glass onto a flexible Polyimide substrate and to be integrated
into a specific miniaturised packaged device for in-vivo testing.