Microelectromagnet for magnetic manipulation in lab-on-a-chip systems

We demonstrate a simple scheme for fabrication of microelectromagnets consisting of planar spiral coils semi-encapsulated in soft magnetic yokes using conventional microfabrication techniques. The microelectromagnets are suitable for applications operating at frequencies below 250 kHz. Conventional fabrication schemes for planar microelectromagnets typically rely on five mask steps. We allow the current to flow in the soft magnetic yoke and thereby two mask steps are eliminated. We have characterized the electromagnets electrically, the results agree well with theory, and the implications arising from current flowing in the magnetic yoke are discussed. We have integrated the microelectromagnets with microfluidic channels, and demonstrated separation of commercially available magnetic beads from a fluid in a microfluidic system, i.e. a lab-on-a-chip system.     

Dilaton as the Higgs boson

We propose a model where the role of the electroweak Higgs field is played by the dilaton. The model contains terms which explicitly violate gauge invariance; however, it is shown that this violation is fictitious, so that the model is a consistent low-energy effective theory. In the simplest version of the idea the resulting low-energy effective theory is the same as the top mode standard model.     

Towards a programmable magnetic bead microarray in a microfluidic channel

A new hybrid magnetic bead separator that combines an external magnetic field with 175 μm thick current lines buried in the back side of a silicon wafer is presented. A microfluidic channel was etched into the front side of the wafer. The large cross-section of the current lines makes it possible to use larger currents and obtain forces of longer range than from thin current lines at a given power limit. Guiding of magnetic beads in the hybrid magnetic separator and the construction of a programmable microarray of magnetic beads in the microfluidic channel by hydrodynamic focusing is presented.     

Universal scaling in transient creep

We present experimental evidence that pressure solution creep does not establish a steady-state interface microstructure as previously thought. Conversely, pressure solution controlled strain and the characteristic length scale of interface microstructures grow as the cubic root of time. Transient creep with the same scaling is known in metallurgy (Andrade creep). The apparent universal scaling of pressure solution transient creep is explained using an analogy with spinodal dewetting.     

Republication of: Observations in cosmology

This is a reprinting of a paper by Jerome Kristian and Rainer K. Sachs, first published in 1966, in which they proposed a power-series scheme for reading out various parameters of the Universe directly from observations in a model-independent way. The paper has been selected by the Editors of General Relativity and Gravitation for re-publication in the Golden Oldies series of the journal. This republication is accompanied by an editorial note written by George Ellis and by a brief biography of J. Kristian, compiled by A. Krasiński from internet sources.     

Simulation of 3D inclined/rotated UV lithography and its application to microneedles

A 3D model is set up to simulate the exposure process of inclined/rotated UV lithography for negative SU-8 resists. The formation of inclined resist pillars and microstructures with truncated cone shapes is simulated based on a 3D exposure model in combination with a post exposure bake model for chemically amplified resists and the Mack development model. As one of the interesting applications employing this promising lithography technique for MEMS fabrication, a solid microneedle for drug delivery is simulated.