pH Measurement using in house fabricated interdigitated capacitive transducer

Microelectronics technologies have contributed a lot of facilities to fabricate small scale devices especially in biological and medical fields where the full advantage in development of transducers and sensors which are capable of characterizing bio-species. The research about the characterisation of fabricated electrode transducer using biomolecule detection technique has been studied to understand the important relationship between the transducer and the structure which leads to high sensitivity and selectivity. This paper mainly illustrate regarding the fabrication process of Interdigitated capacitive sensor (IDC) based sensor for bio-molecular detection process. We have applied conventional photolithography technique by using metal deposited on silicon substrate to fabricate a microelectrode transducer and employed as electrochemical microelectrode sensors to measure the bio-molecules electrical characteristics. IDC mask is designed by using auto-cad software which tailors for detection of bio substance which is extremely small scale in size. IDC mask is patterned transfer on sample by using conventional lithography process which the parameters are critically adjusted to ensure that the pattern transfer process occur with minimal defects. The fabricated sensor will be further validated through electrical and morphological characteristic. The morphological characterizations were carried out using High power microscope (HPM), Atomic force microscope (AFM) and a Scanning electron microscope (SEM). The electrical measurements were carried out using Dielectric analyser (DA) and a source meter. Capacitance test and impedance test is taken with various pH solution to observe the response of the sensor with different pH values. Purchased pH buffer solutions which varied from pH1 to pH12 are dropped on the microelectrode and the effect on it is investigated for the application in pH measurement. This research has proven that increase in pH value from acidic to alkaline- is proportional with capacitance. The measured values of capacitance with respect to each pH concentrations applied during the measurements were repeatable and reproducible.