The effect of the anodization voltage changes on the electric resistance of porous anodic alumina barrier layer and its thickness used in strain sensing devices

Strain sensing is the aptitude to measure the mechanical/electrical and other responses towards strain in a material. In this regard, various types of nanocomposite strain sensors have been developed. For strain sensing applications, various aluminum nanomaterials and other nanoparticles have been used. To investigate the influence of aluminum anodization voltage on the barrier layer thickness of porous anodic alumina (PAA) and its electric resistance used in strain-sensing technology, samples in different voltages, and various conditions of mild and hard anodization were fabricated. Measurement of electrical resistance of barrier layer during the voltage change shows that there is a transition region in which electric resistance of samples is located between hard and mild anodized region. The SEM investigation reveals that the barrier layer thickness is linearly proportional to the anodization voltage. But the barrier layer resistance in hard anodization is lower than that one in mild anodization. The observed paradox can be related to higher ionic mobility of ions in the barrier layer which is formed in hard anodization.