In vitro biosensing based on magnetically induced motion of magnetic nanoparticles

A. Dangl, G. Kokkinis, F. Keplinger, I. Giouroudi
Vienna University of Technology, AT

Keywords: biosensors, microfluidics, magnetic particles


A method for in-vitro detection of bioanalyte using conductive microstructures to accelerate magnetic nanoparticles (MAPs) in an integrated microfluidic system is presented. The fundamental idea behind the elaboration of such a biosensing system is that the induced velocity of MAPs in suspension, while imposed to an identical magnetic field gradient, is inversely proportional to their volume. Therefore, the volumetric increase of MAPs due to binding of bioanalyte onto their surface, changes consequently the velocity of the MAPs. One of the greatest challenges in on-chip biosensing utilizing magnetic methods is to develop micro-sized magnetic field generators. They need to produce magnetic field gradients strong enough to accelerate the MAPs towards a sensing area and to be integrated to microfluidic systems. The presented system addressed this challenge; the acceleration is achieved through sequentially actuated, conductive microstructures, controlled by a programmable microcontroller. These microstructures were readily integrated in a complete microsystem. Two microfluidic channels were fabricated on top of the conductors; one as reference channel for a reference sample. The fabrication was realized using a standard photolithography process and a dry photoresist thin film (Ordyl SY355). A simple, cost effective and reliable detection method which considerably reduces the measurement complexity is reported.