O. Ergeneman

Superparamagnetic photocurable nanocomposite for the fabrication of microcantilevers

We present a photocurable polymer composite with superparamagnetic characteristics for the fabrication of microcantilevers. Uniform distribution and low particle agglomeration (<50 nm) in the photocurable polymer matrix SU-8 are achieved by using superparamagnetic nanoparticles with a surfactant. Particles and composite are characterized by a transmission electron microscope, UV-VIS spectrometer and magnetic measurements. The composite contains 5 vol.% (18 wt.%) of Fe3O4 nanoparticles with diameters of 12.1 ± 3.5 nm. The composite exhibits a magnetization saturation of 13.2 kA m −1 . Superparamagnetic composite microcantilevers with typical dimension of 2 μm × 14 μm × 80‐300 μm are successfully fabricated by two conventional photolithography steps and a sacrificial layer etch. Exposure doses of 10000 mJ cm −2 must be applied for microcantilever thicknesses of 1.8 μm due to the high UV absorption of the particles in the composite. The magnetic polymer cantilevers are successfully actuated in resonance in air with an amplitude of 29 nm. An off-chip coil is used to generate a magnetic field to actuate the cantilevers. (Some figures in this article are in colour only in the electronic version)

Electroplated porous polypyrrole nanostructures patterned by colloidal lithography for drug-delivery applications

Porous nanostructures of polypyrrole (Ppy) were fabricated using colloidal lithography and electrochemical techniques for potential applications in drug delivery. A sequential fabrication method was developed and optimized to maximize the coverage of the Ppy nanostructures and to obtain a homogeneous layer over the substrate. This was realized by masking with electrophoretically-assembled polystyrene (PS) nanospheres and then electroplating. Drug/biomolecule adsorption and the release characteristics for the porous nanostructures of Ppy were investigated using rhodamine B (Rh-B). Rh-B is an easily detectable small hydrophobic molecule that is used as a model for many drugs or biological substances. The porous Ppy nanostructures with an enhanced surface area exhibited higher Rh-B loading capacity than bulk planar films of Ppy. Moreover, tunability of surface morphology for further applications (e.g., sensing, cell adhesion) was demonstrated.

Characterization of Puncture Forces for Retinal Vein Cannulation

For this study, we have collected puncture force data from the vasculature of the chorioallantoic membranes (CAM) of developing chicken embryos to examine forces required for retinal vein cannulation. The CAM vessels of a developing chicken embryo have been shown to be an appropriate model for human retinal veins. The effect of microneedle geometry and vessel size on puncture forces was investigated. The results of this work are important for researchers working on robotic vitreoretinal surgical systems. [DOI: 10.1115/1.4005318]

Superparamagnetic photosensitive polymer nanocomposite for microactuators

We present a photosensitive polymer composite with superparamagnetic characteristics for the fabrication of microactuators. A uniform distribution of particles in the photosensitive polymer matrix SU-8 is achieved by applying superparamagnetic nanoparticles with the aid of a surfactant. The composite contains Fe3O4 nanoparticles up to 3 vol.% (12 wt.%) with diameters of around 13 nm. Superparamagnetic composite microcantilevers are successfully fabricated and actuated in resonance by the magnetic field of an external coil.

Miniaturized magnetic force sensor on a catheter tip

This paper reports the smallest magnetic force sensor integrated on a catheter tip. The sensor is capable of high sensitivity and robust force measurements suitable for invivo applications. It utilizes a magnet mounted on a flexible membrane encapsulating the catheter and a Hall sensor to detect the magnetic field generated by the magnet. The proposed device can be used in many applications of minimally invasive surgery (MIS) to detect forces applied on tissue during procedures or to characterize different types of tissue for diagnosis.

An in-plane cobalt-nickel microresonator sensor with magnetic actuation and readout

We present magnetic microresonators that utilize magnetic actuation and readout for use as mass sensors. A magnetic readout method was developed for the detection of microresonator vibration. Together with wireless actuation, the wireless magnetic readout results in completely passive microresonators. The magnetic readout is based on the induced voltage on a pair of differential pick-up coils, which is generated by the movement of the magnetized microresonator. The successful operation of the readout was demonstrated with CoNi microresonators under atmospheric pressure and in water. The microresonator can be readily functionalized and used as a mass sensor for bio applications.