In-situ thermal conductivity measurement of magnetic nanoparticle layers in Lab-on-a-Chip devices

A measurement setup is presented for the in-situ thermal characterisation of a dense magnetic nanoparticle layer consisting of 500 nm epoxy covered iron oxide particles. The nanoparticles are magnetically trapped in a microchamber as in a Lab-on-a-Chip device. A copper cylinder was embedded into a PDMS microfluidic chip which provides a better signal to noise ratio during the measurements. FEM simulation was also performed to investigate the heat flow through the structure. The experimental results show that the in-situ measurement is possible and the effective thermal conductivity of the dense nanoparticle layer is roughly 60% of that of the distilled water.