Built-in Test Solutions for the Electrode Structures in Bio-Fluidic Microsystems

Electrodes are fundamental to the reliable operation of a new generation of portable bio-analytical instruments based around microsystems technology. The importance of eliminating false positives and false negatives for these instruments is driving work around embedded test, condition monitoring and both diagnostics and prognostics. This paper proposes two solutions for detecting degradation in electrodes that interface to fluidic or biological systems and form the basis of numerous actuation and sensing mechanisms in the bio-fluidics area. A low frequency, impedance based method for identifying degraded structures within an array is proposed that is backed up by physical measurements from an electrode array for drug testing on cardiac and neuron tissue. In addition, a mid-frequency oscillation test is proposed which is based on the sensitivity of the bio-fluidic interface capacitance to degradation, contamination and fouling.