Real-time observation of the actual contact area between surface interfaces at the nanoscale enables more precise examination of what happens during friction. We have combined micro electro mechanical system actuators and transmission electron microscopy (TEM) observation, to both apply and measure forces across nanoscale junctions and contacts. This custom-designed experimental system can measure the true surface area of a contact site from a lateral viewpoint, while simultaneously measuring the friction force. We scratched surfaces coated with diamond like carbon, a classical solid lubricant, and observed the formation of wear particles that slipped and rolled between the interface. TEM images showed that the shape of the surface at the nanoscale underwent permanent deformation when acted upon with forces as low as several tens of nano newtons. The results demonstrated the limitations of friction analyses relying on friction force measurements without real-time surface profiling.

Liquid cells are hermetically sealed capsules that make it possible to image through liquids at the nanoscale using transmission electron microscopes (TEM). Until recently liquid cells can be passive vessels or integrate electrodes for electrodeposition experiments. Temperature is a key parameter for the chemical kinetics of certain processes. This paper describes a temperature controlled liquid cell for in situ TEM studies. The liquid cell integrates a resistive element for both heating and sensing temperature. A capacitively coupled heat feedback technique is implemented to control the temperature of the liquid cell from room temperature to 100 °C with an accuracy of ±0.1 °C. In situ TEM experiments illustrate the heating capability of such temperature controlled liquid cells observed at the nanoscale.

The adaptability of microscale devices allows microtechnologies to be used for a wide range of applications. Biology and medicine are among those fields that, in recent decades, have applied microtechnologies to achieve new and improved functionality. However, despite their ability to achieve assay sensitivities that rival or exceed conventional standards, silicon-based microelectromechanical systems remain underutilised for biological and biomedical applications. Although microelectromechanical resonators and actuators do not always exhibit optimal performance in liquid due to electrical double layer formation and high damping, these issues have been solved with some innovative fabrication processes or alternative experimental approaches. This paper focuses on several examples of silicon-based resonating devices with a brief look at their fundamental sensing elements and key fabrication steps, as well as current and potential biological/biomedical applications.

Liquid cells for transmission electron microscopy enable the observation of liquid samples with nanometer resolution, but sample activity must often be triggered via external stimuli including liquid flow and mixing. Existing devices enable flow using specialized TEM holders and external pumping setups which limits technique accessibility. Here, a liquid cell with integrated MEMS valves and pumps is demonstrated with flow capabilities using an electrical-contact holder. On-chip electrochemical pumps and capillary burst valves allow for the injection of fluid from an integrated reservoir into an observation chamber using only electrical signals from a general microchip-sized TEM holder.

Electrostatic microactuators require external DC biasing in order to achieve the widest possible range of displacements for a given AC input. This report proposes a novel microspeaker structure that utilizes a potassium-ion-electret to reduce the need for such DC voltage application. Electrets exhibiting quasi-permanent charges enable large fixed voltages to be integrated directly within the MEMS structure, acting as an ersatz DC bias. Prototype devices were fabricated and characterized to approximate the effects of electret incorporation on the device performance.

Atomic force microscopy (AFM) uses a scanning stylus to directly measure the surface characteristics of a sample. Since AFM relies on nanoscale interaction between the probe and the sample, the resolution of AFM-based measurement is critically dependent on the geometry of the scanning probe tip. This geometry, therefore, can limit the development of related applications. However, AFM itself cannot be effectively used to characterize AFM probe geometry, leading researchers to rely on indirect estimates based on force measurement results. Previous reports have described sample jigs that enable the observation of AFM probe tips using Transmission Electron Microscopy (TEM). However, such setups are too tall to allow sample tilting within more modern high-resolution TEM systems, which can only tilt samples less than a few millimeters in thickness. This makes it impossible to observe atomic-scale crystallographic lattice fringes by aligning the imaging angle perfectly or to view a flat probe tip profile exactly from the side. We have developed an apparatus that can hold an AFM tip for TEM observation while remaining thin enough for tilting, thereby enabling atomic-scale tip characterization. Using this technique, we demonstrated consistent observation of AFM tip crystal structures using tilting in TEM and found that the radii of curvature of nominally identical probes taken from a single box varied widely from 1.4 nm for the sharpest to 50 nm for the most blunt.