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

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

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

Scanning force microscopy in the dynamic mode using microfabricated capacitive sensors

We report on the first successful operation of a scanning force microscope using microfabricated capacitive force sensors. The sensors, which are made from single crystal silicon on insulator wafers, consist of a cantilever spring with integrated tip at the free end and an electrically insulated counter electrode. Dynamic force gradient sensing is the preferred operating mode. Here, tip–sample interactions are detected by letting the sensor act as a resonator in a phase controlled oscillator setup and measuring corresponding shifts of the oscillation frequency. Experiments were performed in vacuum using a standard tunneling microscope. A Cr grating on a quartz substrate served as the test sample. Topographic images showing details on a 10 nm scale were obtained operating at a constant force gradient of the order of 0.01 N/m. In addition, critical design parameters are discussed based on an analysis of the electromechanical properties of the sensors

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

Micromachined silicon cantilevers and tips for bidirectional force microscopy

A monocrystalline silicon lever with an integrated silicon tip for a force/friction microscope was realized. Theoretical studies have been carried out to find the shape and dimensioning according to the mechanical system requirements. Moreover, sharp tips with a high aspect ratio could be demonstrated

Silicon cantilevers and tips for scanning force microscopy

Monocrystallme slhcon cantilevers with integrated silicon tips for scanning force mlcroscopy are fabriated by means of micromachining techniques Theoretical considerations including finite element modeling have been carried out in order to find a suitable shape and dimensions according to the mechanical requirements. Several different cantilever designs have been fabricated a simple beam with various cross se&Ions as well as a folded meander shape with square cross section. Special attention has been paid to the application of these silicon microprobes to measure friction. Moreover, high-aspect-ratio silicon tips with variable geometries are presented and their integratlon onto cantilevers is demonstrated. Finally, the fabrication of an array of such microprobes is described, which enables multiple parallel or serial surface profiling to be achieved. These integrated micromachmed cantilevers have been successfully applied in standard atomic force microscope measurement systems