Capillary adhesion of microparticles was analytically calculated, modelled by finite element method (FEM) simulations and measured. The effects of elastic deformation and liquid adsorption were analyzed. By means of an atomic force microscope, we measured the force between a silica bead of 2 mm radius and a planar polydimethylsiloxane surface (Young's modulus E ¼ 1 MPa) in the presence of ethanol at different vapor pressures. Results were compared to adhesion forces measured on a silicon wafer.Independent of the sample elastic modulus experiments showed a monotonous decrease of capillary forces with increasing ethanol partial vapor pressure for P/P sat > 0.2, where P sat is the saturation vapor pressure. However, adhesion forces on the soft surface were much stronger than on the rigid silicon wafer. In order to explain the experimental results, a previous developed theory (Soft Matter, 2010, 6, 3930) was extended to take into account vapor adsorption of ethanol. Analytical calculations were compared to results of FEM simulations where the detailed deformation of the elastic support close to the meniscus was explicitly taken into account.

Mechanical properties of ultra‐thin organic films are fundamentally important in coating applications. Micromechanical cantilever sensor (MCS) and laser‐based surface acoustic wave (LA‐SAW) techniques were both used to measure Young's moduli (E) of plasma polymerized films at different humidities (H). For plasma polymerized allylamine (ppAA) films deposited at 5 W and 90 W, E of 1400 ± 350 MPa and 110 ± 20 MPa at H between 10 and 40%, and 1070 ± 250 MPa and 32 ± 10 MPa at H between 70 and 80% were measured. The LA‐SAW technique revealed E lower than 60% of that measured by MCS. The difference suggested either an enhanced swelling at the air interface or a gradient of cross‐linking density.

In this paper, we apply a digital holographic microscope (DHM) in conjunction with stroboscopic acquisition synchronization. Here, the temperature-dependent decrease of the first resonance frequency (S1(T)) and Young’s elastic modulus (E1(T)) of silicon micromechanical cantilever sensors (MCSs) are measured. To perform these measurements, the MCSs are uniformly heated from T0 = 298 K to T = 450 K while being externally actuated with a piezo-actuator in a certain frequency range close to their first resonance frequencies. At each temperature, the DHM records the time-sequence of the 3D topographies for the given frequency range. Such holographic data allow for the extracting of the out-of-plane vibrations at any relevant area of the MCSs. Next, the Bode and Nyquist diagrams are used to determine the resonant frequencies with a precision of 0.1 Hz. Our results show that the decrease of resonance frequency is a direct consequence of the reduction of the silicon elastic modulus upon heating. The measured temperature dependence of the Young’s modulus is in very good accordance with the previously-reported values, validating the reliability and applicability of this method for micromechanical sensing applications.

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