A magnetic-field-sensing system that consists of a miniature zero-power magnetometer, an integrated micromachined corner-cube reflector (CCR), a commercially available diode laser, and a photodetector array, has been designed, fabricated, assembled, and tested. The zero-power-magnetometer design is based on a ferromagnetic MEMS magnetometer, which consists of a permanent magnet that is torsionally suspended to allow rotation about a single axis. A single mirror of the CCR is attached to the magnetometer torsion beam. When the magnet rotates in response to a change in magnetic field, the torsion beam will twist and cause the mirror to become misaligned. The non-ideality of the CCR can be interrogated with a laser and a photosensor array can be used to measure the reflected signal. This method of magnetic sensing completely eliminates sensor-node power consumed at the remote location. The sensor node developed for this paper occupies a volume of only 1.5 mm 3 and can detect a magnetic field between 820 A/m to 6 kA/m with an uncertainty of 90 A/m at a 1-m optical-interrogation range. The primary application of this technology is in wireless sensing systems that must operate continuously without providing or maintaining the sensor-node energy (e.g., replacing batteries or scavenging energy) or in extremely harsh environments where power supplies and integrated circuits (IC) are not an option.[1616]

The most common treatment for patients with hydrocephalus is the surgical implantation of a cerebrospinal fluid (CSF) shunt. Unfortunately, this device, which is critical for lowering intracranial pressure, has a substantial failure rate (40% in the first year). A leading cause of failure is the obstruction of the ventricular catheter. The goal of this project is to design a ventricular catheter that will resist occlusion through the use of micromachining and micro electro-mechanical systems (MEMS) technologies. We designed, fabricated, and tested magnetic microactuators. The theoretical results show that the fabricated microactuators can produce the force necessary to remove an adherent cellular layer grown over the actuator surface. By integrating the microactuators into the catheters, we hope to produce an improved catheter with the ability to actively combat the health-threatening occlusion process.

Building upon prior work performed at the micrometer scale, nanometer-scale flexure-based ferromagnetic actuators have been designed, fabricated, and tested. The smallest fabricated and tested magnetic actuator is a cantilever-based ferromagnetic actuator that consists of a single 50×338×1500 nm 3 nickel magnet and a 30×110×2200 nm 3 gold cantilever beam. In addition, the ultimate scaling limits of actuators of this general design have also been carefully studied and presented. The targeted applications for these structures include magnetically tunable frequencyselective surfaces, tunable optical filters, and direct macroto-nano 3-D manipulation performed in a wide variety of nanoscale environments.

The near-surface mounted (NSM) strengthening technique, in which pultruded fiber reinforced polymer (FRP) plates or bars are adhesively bonded into grooves cut in the concrete cover, has proven to overcome several of the drawbacks of externally bonded FRP plates on reinforced concrete flexural members. However, as research on the NSM technique is relatively recent, the theoretical foundation for its application is not yet as complete, and some of the debonding mechanisms are not yet fully understood. This paper presents the main findings of a literature review aimed at identifying the existing analytical models to predict the debonding strength of reinforced concrete flexural elements retrofitted with NSM FRP strips, and of a thorough assessment of the adequacy of such models by comparison with all relevant published experimental data. It is concluded that for debonding of NSM FRP strips induced by flexural (or flexural-shear) cracking or the critical diagonal shear crack of the reinforced concrete member, the currently available models capture the behavior of the debonding mechanism and provide reasonably conservative estimations of the debonding strength. However, for debonding induced by stress concentrations at the strip ends, existing models do not fully capture the debonding behavior and as such, are shown to be excessively conservative.