Detection of sample conductivity and bacterial presence using inductive microcoils. Effect of device size and geometry

In a previous work, we demonstrated that inductance monitoring using microcoils allows straightforward discrimination of solutions containing different salt or bacteria concentrations [1]. As it is shown here, the microfabrication method can be significantly simplified as to produce cheaper, easier to fabricate and more robust sensors by CMOS technologies. Besides, we compare the performance of 12 microcoil types exhibiting different geometric features. In this context, the effect of a number of parameters on sensorʹs performance, including microcoil active area, inductance nominal value, sample volume and measurement frequency, has been studied and discussed. The results confirm that inductive microcoils can be used as efficient conductivity sensors for the study of sample microvolumes.