Control of objects in nanofluidic confinement
“We strive to use this method to explore novel concepts for the control, transport, separation and positioning of particles.”
—IBM scientist Armin Knoll
In nanofluidic confinement the particle-surface interactions depend strongly on the separation from the surfaces. Accordingly, by shaping the topography of the surfaces the interaction can be modulated and the particles experience an energy landscape designed by the topography. We strive to use this method to explore novel concepts for the control, transport, separation and positioning of particles.
The Nanouidic Confinement Apparatus: Studying confinement dependent
nanoparticle behavior and diffusion
S. Fringes, F. Holzner, A.W. Knoll
To be published (2017).
We present a versatile setup for investigating the nanofluidic behavior of nanoparticles as a function of the gap distance between two confining surfaces. The setup is designed as an open system which operates with small amounts of dispersion of ≈20µl, permits the use of coated and patterned samples, and allows high-numerical-aperture microscopy access.
In situ contrast calibration to determine the height of individual diffusing nanoparticles in a tunable confinement
S. Fringes, M. Skaug, A.W. Knoll
J. Appl. Phys., 119, 024303 (2016).
We study the behavior of charged spherical Au nanoparticles in a nanoﬂuidic slit as a function of the separation of the symmetrically charged conﬁning surfaces. A dedicated setup called the nano-ﬂuidic conﬁnement apparatus allows us to parallelize the two conﬁning surfaces and to continuously approach them down to direct contact. Interferometric scattering detection is used to measure the particle contrast with 2 ms temporal resolution. We obtain the conﬁnement gap distance from the interference signal of the glass and the oxide-covered silicon wafer surface with nanometer accuracy. We present a three parameter model that describes the optical signal of the particles as a function of particle height and gap distance.
Directed Placement of Gold Nanorods Using a Removable Template for Guided Assembly
F. Holzner, C. Kuemin, P. Paul, J.L. Hedrick, H. Wolf, N.D. Spencer, U. Duerig, A.W. Knoll
Nano Lett., 11, 3957-3962 (2011).
We have used a temperature sensitive polymer film as a removable template to position, and align, gold nanorods onto an underlying target substrate. We demonstrated both the placement and orientation of nanorods with an overall positioning accuracy of ≈ 10 nm onto an unstructured target substrate.