Test Strategies for Electrode Degradation in Bio-Fluidic Microsystems

Electrode technology is fundamental to numerous actuation and sensing functions in bio-fluidic microsystems that target portable bio-analytical instruments. Within these systems high levels of reliability and robustness are crucial and normally complemented by requirements for extremely low probabilities of false positives or negatives being generated. New methods of validating functionality and integrity of the reading are hence required. Embedded test and condition monitoring are crucial technologies for delivering these capabilities. This paper presents two solutions for detecting degradation in electrodes that interface to fluidic or biological systems. In the first solution, a low frequency, impedance based method for identifying degraded structures within an array is proposed. This method depends on measuring and comparing the impedance of each sensing electrode. This research is backed up by physical measurements from an electrode array for drug testing on cardiac and neuron tissue. In the second solution, a mid-frequency oscillation test technique is proposed that is sensitive to degradation in the bio-fluidic interface capacitance, to contamination and to fouling.

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