Integrated inductances for Si-technology based high sensitivity biosensors

Inductive integrated devices for bio-sensing applications are simulated, designed and fabricated. These devices are based in the use of magnetic particles as markers of the biomolecule to be detected. The sensing principle of the device is related to the changes of the coil inductance determined by the presence of different densities of magnetic particles in the active device area. The devices are simulated assuming a continuous layer with an effective magnetic permeability /spl mu//sub ef/ which is given by the density of particles. This simulation has allowed analysing the influence of the different device parameters on the sensor response. Accordingly, a set of integrated coils with different dimensions (from 50 /spl mu/m up to 500 /spl mu/m) and number of turns has been fabricated using a two metal levels technology. Simulation of these devices gives inductance changes in the range 0.05-80 nH and sensitivities in the range 2-8% for /spl mu//sub ef/ = 10. The preliminary electrical characterisation of the devices agrees with their simulation, being the analysis of their sensor behaviour under progress.