A magnetostrictive bending sensor with rectangular planar coil is investigated. Its purpose is to measure contactlessly
mechanical quantities of non-vibrating structures using an alternating magnetic field. The coil turns are electrodeposited
by pattern plating on top of a magnetostrictive Galfenol layer and a thin isolation layer. The coil turns investigated in this
paper were manufactured with a constant height of 10 μm and gap of 20 μm but variable width.
The sensor is operated near its electrical self-resonance between 5 and 40 MHz and requires a high quality factor. FEMsimulations
show that the quality factor of circular planar coils is almost independent on the conductor width under the
given design restrictions when skin and proximity effects are included.
Analytical calculations of rectangular coil parameters with three different turn numbers and conductor widths depending
on the turn number predict an almost constant self-resonance quality factor in the DC case. Measured self-resonance
quality factors are up to 59 % lower. The main reason for the disagreement is the current crowding by the proximity
effect since analytical calculation show a significant influence of the skin effect only at higher frequencies with respect
to the investigated self-resonance frequencies. Compared to the results of an FEM analysis obtained for circular coils the
proximity effect is much smaller as well as the achievable low frequency quality factor.
Liposomes are self-assembled spherical vesicles comprised of a lipid bilayer membrane that segregates an
internal aqueous environment from an external aqueous environment. These nanometer-scale structures
have demonstrated potential for targeted drug delivery applications. For liposomes to be useful in vivo, the
liposome size and dosage of molecules contained within them needs to be controlled. We present here a
fluorescence-based technique for characterizing the relative encapsulation efficiency, leakage rate, and
shelf life of liposome formulations. We report results from three different liposome solutions over a period
of two months that show the liposome brightness remains stable while the background dye concentration
increases. These parameters may prove useful for optimizing the liposome formation process.
A vertically sensitive acceleration sensor has been fabricated by combining the low-cost UV-LIGA process with a sacrificial layer technique. The key structure of the sensor is an asymmetric proof-mass which is suspended over two stationary electrodes. Because of the asymmetric arrangement of the proof-mass, an acceleration in the Z-direction results in an opposite deflection of its large and small parts. Hence, the acceleration can be detected by the differential capacitor arrangement between the proof-mass and the two stationary electrodes. The fabrication of this vertically sensitive accelerometer is a planar batch procedure comprising only a few processing steps. The entire structures are first grown electrochemically within the UV- patterned thick AZ4562 photoresist on an electroplating base that composes of rigid and sacrificial layers. Moveable Ni- parts are then obtained by removing the underneath titanium sacrificial layer using wet etching. Sensor structures up to 30 nm with an aspect ratio of about 10:1 can be reliably manufactured. It is thought that this fabrication approach can be widely applied to economically realize other micromechanical components with oscillating structures. Design and realization of the vertically sensitive accelerometer is described in this paper.