Carbon nanotubes (CNTs) can be grown in dense lithographically patterned forests to form framework structures that can be filled in via chemical vapor deposition to form solid structures. These solid structures can then be used in microelectromechanical systems (MEMS) applications. Initial testing with these structures suggests that when these frameworks are filled with carbon, the resulting material exhibits favorable properties for use in compliant MEMS. To better understand this material's properties, we conducted tests to measure its Young's modulus, failure stress, and stress relaxation in the direction perpendicular to the CNT growth, as well as the modulus and stress in the direction parallel to the CNTs. To determine the properties in the transverse direction, we applied vertical loads to the tips of simple cantilever beam samples, and recorded the force and deflection until failure. The results showed failure strain up to 2.48%. Cantilever samples prepared from the same pattern were also used to measure the stress relaxation of the material. The first test for each sample showed an average force relaxation of 3.72%, while successive tests only produced 1.23% after 24 h. To determine the properties in the direction parallel to the CNTs, we prepared simple rectangular beams and subjected them to 3-point bending tests. The average strain calculated in the parallel direction was 8.17%.[2013-0121] Index Terms-Micromechanical devices, carbon nanotubes, material properties.

A new, compact 2 degree-of-freedom mechanism 4.1 mm in diameter suitable for robotically controlled surgical operations is presented. Current commercially available robotically controlled instruments achieve high dexterity defined by three degrees of freedom and relatively confined swept volume at just under 1 cm in diameter. Current smaller diameter instruments result in high part count and large swept volumes (less dexterity). A meso-scale rolling contact gripping mechanism is proposed as an alternative. The manufacturing of the parts is made feasible by Metal Laser Sintering, which can produce parts that are difficult to replicate with traditional manufacturing methods. The resulting instrument has only 6 parts and a small swept volume. Instrument actuation and control by a surgical robotic system is demonstrated.

This paper presents a method for fabricating millimeter-scale robotic components for minimally invasive surgery. Photolithographic patterning is used to create a framework of carbon nanotubes (CNTs) that can be infiltrated with a variety of materials, depending on the desired material properties. For the examples shown in this paper, amorphous carbon is used as the infiltration material. The planar frameworks are then stacked to create the 3D device. The detail and precision are affected by large changes in cross section in the direction of stacking. Methods for improving the definition of the 3D object due to changing cross section are discussed. The process is demonstrated in a two-degree-of-freedom (2DOF) wrist mechanism and a 2DOF surgical gripping mechanism, which have the potential of decreasing the size of future minimally invasive surgical instruments.

This article provides an overview of using mobile technology in the classroom to enhance assessment of student learning. Although research on mobile devices in education is still in the embryonic stage, students generally have positive views about using their mobile devices for classroom polling and backchannel communication. However, there are also several challenges including the increased opportunity to be distracted when using mobile devices for other purposes, cost of the technology, and privacy concerns. The information presented will serve as a focal point for future research regarding the use of mobile technology in the classroom, and may help teachers to find new ways to reach their students.

Abstract. This paper presents a design and a method for fabricating and testing fully compliant, bistable threshold accelerometers made from a carbon-infiltrated carbon nanotube framework. Two different configurations based on differences in compliant beam angles are presented. Both configurations were tested under constant accelerations produced by mounting them on a spinning disk and under impulse accelerations by mounting them to the end of a swinging pendulum with a stop at the lowest point of the pendulum path. Tests were also performed to observe the potential effects of stress relaxation in the carbon nanotube material. This was done by placing the accelerometers in their second stable position (nonfabricated position) and then testing them after a period of 24 h. Results show that in eight of the twelve tests there was no significant change due to stress relaxation. In the other four tests, the change was relatively small, especially when compared to stress relaxation effects in other materials such as plastics. Measurements indicate that the accelerometers show very high repeatability individually. However, we also observed that there is significant variation in switching acceleration between accelerometers with identical geometric parameters. This may be due to random variation occurring during the fabrication process.