Surface-micromachined Ta–Si–N beams for use in micromechanics

Realization and characterization of free-standing surface-microstructures based on Ta-Si-N films are presented. Due to their significant physical and chemical properties, such ternary films are promising candidates for application in microelectromechanical devices

Response to Dr Greenwood’s Comments on “Extending the Double-Hertz Model to Allow Modeling of an Adhesive Elliptical Contact”

© 2018, The Author(s). An adhesive elliptical contact is normally found in microscale applications that involve cylindrical solids, crossing at an angle between 0° and 90°. Currently, only one model is available to describe the elliptical contact’s surface interaction: the approximate Johnson–Kendall–Roberts (JKR) model which is limited to soft materials. In this paper, a new adhesive elliptical model is developed for a wide range of adhesive contacts by extending the double-Hertz theory, where adhesion is modeled by the difference between two Hertzian pressure distributions. Both Hertzian pressures are assumed to have an equivalent shape of contact areas, the only difference being in size. Assuming that the annular adhesive region is obtained by the area difference between the two Hertzian contact areas, the pull-off force curves can be calculated. In the limiting case of an adhesive circular contact, the results are very close to results from the existing models. However, for an adhesive elliptical contact in the JKR domain, lower pull-off forces are predicted when compared to the JKR values. Unlike the developed model, the shape of the JKR contact area varies throughout contact. Results show, particularly for conditions close to the JKR domain, that it is important to take into account that the adhesive region is the result of the two Hertzian contact areas having a non-equivalent shape

Cancer survivors who fully participate in the PROFILES registry have better health-related quality of life than those who drop out

Purpose Attrition and subsequent missing data pose a challenge in longitudinal research in oncology. This study examined factors associated with attrition in the PROFILES registry, and its impact on observed health-related quality of life (HRQOL) estimates. Methods Sociodemographic, clinical, and HRQOL data were collected annually from a cohort of 2625 colorectal cancer survivors between 2010 and 2015. Participant characteristics according to time of dropout were compared using analysis of variance and chi-square tests. Predictors of attrition were examined in logistic regression analysis. Multilevel linear mixed models were constructed to investigate associations between attrition and HRQOL over time. Results Participants who dropped out were more likely to be female (OR = 1.23, CI = 1.02–1.47), older (OR = 1.20, CI = 1.09–1.33), less educated (OR = 1.64, CI = 1.30–2.11), and to have depressive symptoms (OR = 1.84, CI = 1.39–2.44) than full responders, and less likely to have high socioeconomic status (OR = 0.74, CI = 0.61–0.94). Participants who dropped out earlier reported significantly worse HRQOL, functioning, and psychosocial symptoms, which declined at a steeper rate over time, than full responders. Conclusions Cancer survivors’ HRQOL may be overestimated in longitudinal research due to attrition of the most unwell participants. Implications for Cancer Survivors Cancer survivors with the poorest health are at risk of dropping out of PROFILES and possibly withdrawing from other activities. Optimizing participation in PROFILES—a potential mechanism for providing information and access to support—is an avenue for keeping this group engaged

Microlever with combined integrated sensor/actuator functions for scanning force microscopy

A novel silicon microfabricated sensor head for the scanning force microscope (SFM) is presented. The force sensor consists of a cantilever and an adjacent counter-electrode forming the two plates of a capacitor. Force-induced cantilever deflections are monitored by capacitive detection. Typical lever dimensions of 800 um x 40 um and a gap of 3 um yield an active sensing capacitance C=O.l pF. The expected sensitivity in terms of vertical cantilever motion is dC/dz=10 fF/m. In addition to the sensing capability, the microlever can also be z-actuated by applying controlled voltages. This allows both the tip-to-sample distance and the cantilever/system compliance to be adjusted. Expressions are derived for the amplitude of cantilever deflections under electrostatic actuation in the static and dynamic modes as pertinent to applications of SFM in the contact and non-contact modes. The microlever is fabricated using silicon bulk- and surface-micromachining techniques including fusion bonding and sacrificial layer etching. First measurements of the static and dynamic deflections of cantilevers are analysed and show promising results. The reported device basically represents a module of an SFM microsystem with integrated cantilever deflection sensor and adjustment capability