In-situ measurement of nanoparticle quantity in microchambers

A measurement setup and a novel method are presented for the in-situ measurement of the quantity of magnetic nanoparticles (MNPs), which form a dense layer in a microchamber. The layer is formed by 250 nm or 500 nm epoxy covered iron oxide particles. The measurement is based on the resonance frequency shift of an RLC circuit whereas a flat inductor coil integrated in a PDMS film acts as a sensor. The particle amount inside the chamber affects the inductivity therefore the resonance frequency is changed. The method also enables the on-line monitoring of the actual particle quantity in the chamber. Characterization measurements revealed that the storage capacity of the 1 μl chamber is 128 μg and it is independent on the particle size in the 250 nm to 500 nm size range.