Magnetic Actuation

Magnetic actuation principles using superparamagnetic particles suspended in a fluid are studied in this paper. Two experimental setups for different magnetic field settings are designed and fabricated. On the basis of optical velocity measurements, the induced behavior of single and ordered chains was analyzed and compared to theoretical models. Interactions between the particles, fluid and nearby walls induce self-organization phenomena,

Soft-bodied magnetically actuated microrobots could be developed by including controlled dispersions of magnetic nanoparticles into polymeric micro-fabricated structures. The characterization and actuation of magnetically active soft-bodied microrobots by tailored magnetic fields is, thus, a key issue for the design, full control and further development of these mobile micro-systems. In this work, the authors demonstrate the predictable and controllable transportation of polymeric flexible nanofilms embedding super-paramagnetic nanoparticles, by developing and quantitatively validating a model of the magnetic force acting on such structures, thus paving the way towards the wireless magnetic actuation of soft-bodied microrobots. The magnetic forces generated in our experimental conditions range from about 10 –9 to 10–6 N, with typical velocities for the nanofilms ranging between about 0.1 and 2.3 mm/s. For the entire range, a good agreement between theoretical model predictions and measured data is obtained (average normalized error δ =3. 65%). The proposed approach for microrobotic development targets challenging environments, where keywords are liquid or wet micro-structured environments, like in biomedical applications.

In this chapter, we present a hybrid microsystem that combines magnetic actuation with in situ optical detection. The chosen detection mechanism allows the observation and measurement of single magnetic microparticles of different sizes, as well as the detection of fluorescent labels attached to the particles’ surface. We are able to detect mouse IgG as target antigen in a sandwich immunoassay down to a concentration of 0.1 ng/ml. Our work represents a first step toward a full diagnostic LOC system for detection of specific antigens.

A new model of a linear magnetic actuator (LMA) that can be applied to the controllable squeeze film damper (CSFD) was proposed, designed, and fabricated. To validate the operation of the proposed actuator, a mathematical model of the proposed LMA was derived through experiments. From the experimental results it was verified that the electromagnetic force depends upon the position of the mover (the outer damper ring of the CSFD) and the applied current. Also, the electromagnetic force varies symmetrically with the position of the mover within the working region. A self-tuning fuzzy PID controller was applied to control the position of the novel LMA. Further, the proposed LMA was assembled in the squeeze film damper (SFD), where the clearance can be controlled by LMA. To investigate the damping effect of the damper under various clearances by controlling the LMA, experiments on the rotor test-rig were conducted. From the experimental results, the proposed device, which is composed of SFD and LMA, was verified to be very effective for attenuation of the vibration of the rotor system.

This paper proposes a novel method for measuring blood plasma and serum viscosity with a microcan-tilever-based MEMS sensor. MEMS cantilevers are made of electroplated nickel and actuated remotely with magnetic field using an electro-coil. Real-time monitoring of cantilever resonant frequency is performed remotely using diffraction gratings fabricated at the tip of the dynamic cantilevers. Only few nanometer cantilever deflection is sufficient due to interferometric sensitivity of the readout. The resonant frequency of the cantilever is tracked with a phase lock loop (PLL) control circuit. The viscosities of liquid samples are obtained through the measurement of the cantilever's frequency change with respect to a reference measurement taken within a liquid of known viscosity. We performed measurements with glycerol solutions at different temperatures and validated the repeatability of the system by comparing with a reference commercial viscometer. Experimental results are compared with the theoretical predictions based on Sader's theory and agreed reasonably well. Afterwards viscosities of different Fetal Bovine Serum and Bovine Serum Albumin mixtures are measured both at 23 °C and 37 °C, body temperature. Finally the viscosities of human blood plasma samples taken from healthy donors are measured. The proposed method is capable of measuring viscosities from 0.86 cP to 3.02 cP, which covers human blood plasma viscosity range, with a resolution better than 0.04 cP. The sample volume requirement is less than 150 ll and can be reduced significantly with optimized cartridge design. Both the actu-ation and sensing are carried out remotely, which allows for disposable sensor cartridges.

Field selectors can greatly improve the overall performance and versatility of multi-object spectrometers because they allow efficient use of the available detector arrays and data handling capabilities. Here we describe a programmable multi-object field selector currently under development for use in the NGST Near Infrared Spectrometer (NIRSpec). This device is a large microshutter array of 100µm x 100µm shutters fabricated

Purpose–The purpose of this paper is to present a graph representation of the design space that is suitable for the ant colony optimization (ACO) method in topology optimization (TO) problems. Design/methodology/approach–The ACO is employed to obtain optimal routes in an equivalent graph representation of the discretized design space, with each route corresponding to a given distribution of material.

Many microgravity experiments require very low levels of acceleration which cannot be achieved on the International Space Station due to the residual vibration. A vibration isolation system is then usually devised between the experiment and the space station to obtain the desired accelerations at the experiment level. The very low frequency threshold required by the isolation specifications makes passive solutions