Fabrication process development for a high sensitive electrochemical IDA sensor

We present recent results on a development and fabrication process of the electrochemical sensor with high sensitivity. The electrochemical sensor is based on an enzyme-linked immunosorbent assay (ELISA). The used ELISA provides a redox active species as intermediate product for the electrochemical detection. The increase in sensitivity due to the redox cycling process was evaluated with an interdigitated electrode array (IDA) consisting of 300 fingers with 2 μm width and 1 μm gap each. The lithography process was simulated to estimate the impact of the sensor stack and the illumination source during the lithography step on the sensor’s critical features. Development characteristics of the photoresist were precisely determined using a multi-wavelength dissolution rate monitor (DRM). The final sensor was tested with the ferri/ferro cyanide couple as well as with para-aminophenol (PAP). Both results prove amplification factors of more than 10 measured in a flow cell. The results presented demonstrate that high sensitivity electrochemical immunosensors based on redox cycling at IDAs on Pyrex substrate can be fabricated with conventional but highly optimized UV lithography.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Mask aligner exposure simulation of interdigitated electrode arrays can reduce exposure test time and lead to reduce feature size. ► The photoresist was analyzed by dissolution rate monitor. ► The illumination source and mask was optimized by simulation results. ► Redox cycling tests in a flow cell containing para-aminophenol show amplification factors more than 10.