As tribological properties are critical factors in the reliability of microelectromechanical systems, it is important to
understand the physical processes and parameters governing wear and friction in silicon structural films. Dynamic
friction, wear volumes and wear morphology have been studied for polysilicon devices from the Sandia SUMMiT V<sup>TM</sup>
process actuated in ambient air at μN loads. A total of seven devices were tested. Roughly half of the devices showed a
peak in the friction coefficient at three times the initial value with failure after 105 cycles. The other half of the devices
behaved similarly initially; however, following the friction coefficient peak they displayed a lower steady-state friction
regime with no failure for millions of cycles. Additionally, the nanoscale wear coefficient and roughness increased in the
first ~10<sup>5</sup> cycles and then slowly decayed over several million cycles. Transmission electron microscopy studies revealed
amorphous oxygen-rich debris. These measurements show that after a short adhesive wear regime, abrasive wear is the
governing mechanism with failures attributed to differences in the local nanoscale surface morphology. Changing the
relative humidity, sliding speed and load was found to influence the friction coefficient, but re-oxidation of worn
polysilicon surfaces was only found to have an effect after periods of inactivity.
The age-related deterioration in bone quality and consequent increase in fracture incidence is an obvious health concern that is becoming increasingly significant as the population ages. Raman spectroscopy with deep-ultraviolet excitation (244 nm) is used to measure vibrational spectra from human cortical bone obtained from donors over a wide age range (34–99 years). The UV Raman technique avoids the fluorescence background usually found with visible and near-infrared excitation and, due to resonance Raman effects, is particularly sensitive to the organic component of bone. Spectral changes in the amide I band at 1640 cm–1 are found to correlate with both donor age and with previously reported fracture toughness data obtained from the same specimens. These results are discussed in the context of possible changes in collagen cross-linking chemistry as a function of age, and are deemed important to further our understanding of the changes in the organic component of the bone matrix with aging.