In this article, we present novel sample preparation methods using a helium ion microscope (HIM). We report the possibility of reshaping, at room temperature, thin metal lines on an electron-transparent membrane: A set of platinum bridges with standard geometry (300 × 200 × 15 nm) was modified at room temperature into different shapes using focused helium (He)-ion beam. Also the applicability of the HIM as a tool for precise modification of silicon (Si) and strontium titanate (SrTiO3) lamellae is shown and discussed. We demonstrated that in situ heating (e.g., at 600 °C) of the samples during He-beam illumination by use of a specially developed heating stage enables production of thin Si and SrTiO3 samples without significant artifacts. The quality of such cuts was inspected by transmission electron microscopy with high-resolution imaging, and the diffraction patterns were analyzed.

In this article, the effects of substrate temperature on the crystallographic structure and first-order magnetic phase transition in iron-rhodium (FeRh) thin films are investigated. It was found that for the as-deposited FeRh thin films, 350–400 °C is the optimal range of substrate temperature for obtaining B2 ordered FeRh thin films. After postannealing, it was shown that 400 °C is the optimized substrate deposition temperature for obtaining the best chemical/atomic ordering in postannealed FeRh thin films. Magnetization studies indicate that the as-deposited FeRh thin film with substrate temperature of 350 °C does not show a first-order antiferromagnetic (AFM)- to-ferromagnetic (FM) phase transition behavior during heating process and it gives a typical FM behavior whereas the as-deposited FeRh thin film deposited at 400 °C shows a broad first-order AFM-to-FM phase transition during heating and cooling processes. Both the postannealed FeRh thin films deposited at 350 and 400 °C give a clear first-order AFM-to-FM phase transition with a residual magnetization of about 50–100 emu/cc. The residual magnetization may possibly be caused by the disordered bcc (α) FM phase, B2 ordered (α′) FM phase or a near-surface/interfacial ferromagnetism in the ordered FeRh thin films.

Microfluidic paper-based analytical devices (μPADs) use the passive capillary-driven flow of aqueous solutions through patterned paper channels to transport a sample fluid into distinct detection zones that contain the reagents for a chemical assay. These devices are simple, affordable, portable, and disposable; they are, thus, well suited for diagnostic applications in resource-limited environments. Adding screen-printed electrodes to the detection zones of a μPAD yields a device capable of performing electrochemical assays (an EμPAD). Electrochemical detection has the advantage over colorimetric detection that it is not affected by interference from the color of the sample and can be quantified with simple electronics. The accessibility of EμPADs, however, is limited by the requirement for an external potentiostat to power and interpret the electrochemical measurement. New developments in paper-based electronics may help loosen this requirement. This review discusses the current capabilities and limitations of EμPADs and paper-based electronics, and sketches the ways in which these technologies can be combined to provide new devices for diagnostic testing.

Cellulose is one of the most abundant organic materials on earth, and cellulose paper is ubiquitous in our daily life. Re-engineering cellulose fibers at the nanoscale will allow this renewable material to be applied to advanced energy storage systems and optoelectronic devices. In this article, we examine the recent development of nanofibrillated cellulose and discuss how the integration of other nanomaterials leads to a wide range of applications. The unique properties of nanofibrillated cellulose enable multi-scale structuring of the functional composites, which can be tailored to develop new concepts of energy and electronic devices. Tapping into the nanostructured materials offered by nature can offer many opportunities that will take nanotechnology research to a new level.

Paper, broadly defined as thin, porous sheets, is currently being used to create novel devices for diagnostics, microfluidics, and electronics that ideally combine low cost and high performance. A “device,” in this context, can be defined as an object that serves to provide information or function to a user in response to input. This issue will highlight some of these novel devices and provide examples of potential applications. We begin with an overview of paper’s unique properties and how these properties lead to a potential for changing the integrated microfluidic and flexible electronics landscape. We then discuss methods for patterning paper as well as specific fluidic operations that are possible on paper. Finally, we conclude with an overview of electronic devices on paper and a brief outlook on the future of this emerging field.

The need to improve health outcomes in the developing world and to moderate healthcare costs in developed countries has resulted in an increased interest in sophisticated, inexpensive, and instrument-free point-of-care diagnostics using porous materials. One major segment of the paper-based diagnostics effort is focused on developing high-performance point-of-care tests using porous nitrocellulose membranes. This review provides a perspective on the nature, history, and future of nitrocellulose-based assays. Beginning as a protein blotting substrate, porous nitrocellulose membranes have grown to be the most commonly used lateral flow substrate and are the primary membranes used in two-dimensional paper networks for user-friendly multistep assays. In addition to the historical context, we examine assay development considerations, such as the physics of flow in porous media, reagent deposition and storage, and detection methods.