Magnetic and plasmonic nanostructures for bio-nano-electronics

Willem Van Roy
Functional Nanosystems (FNS) group
IMEC, Kapeldreef 75, B-3001 Leuven, Belgium

The entry of micro- and nanotechnologies into the realm of biological systems leads to an exciting
cross-pollination at the cross-roads between physics, materials sciences, chemistry, biomedical
and life sciences. The Functional Nanosystems group at IMEC combines a strong technological
background in nanomagnetism and nanoplasmonics with nanofluidics, nanoparticle synthesis,
and surface functionalization. In this presentation I will give an overview of our activities in the fields
of magnetism, plasmonics, and chemical self-assembly, with focus on biomedical applications.

In many biosensors, labels are selectively attached to the target molecule, antibody, or cell to allow
detection by a suitable transducer. Magnetic labels can be detected using integrated GMR or spin
valve sensors. However, unlike other labels that are only used for detection, magnetic labels can
also be manipulated using local magnetic fields. This provides important additional functionalities
for sample preparation, mixing, purification, isolation, etc.,  and I will show how the integration with
nanofluidics can lead to complete lab-on-chip solutions.

Other activities on biomagnetism in the group include the chemical synthesis of superparamagnetic
nanoparticles for use as contrast agents in magnetic resonance imaging (MRI) and in hyperthermia
applications.

Our second approach is based on nanoplasmonics. The high sensitivity of localized surface plasmon
resonances (LSPR) to their environment is used in label-free biosensing. Large local field enhancements
lead to highly sensitive detection techniques such as surface-enhanced Raman scattering (SERS) that
may allow single molecule detection.

In order to tune the properties of the underlying nanostructures and optimize their performance, we use a
combination of top-down and bottom-up techniques. Examples include chemical self-assembly to fabricate
complex nanoparticles with reduced symmetry, such as core-shell and multilayer structures, open shells,
nanorings, etc. with a wide range of characteristics, and top-down fabrication of antenna and waveguiding
structures to guide and concentrate the optical energy into the desired location.