The jig is up for small soft machines.

A watchmaker's approach yields small, agile, soft machines.

Exploiting Mechanical Instabilities in Soft Robotics: Control, Sensing, and Actuation.

The rapidly expanding field of soft robotics has provided multiple examples of how entirely soft machines and actuators can outperform conventional rigid robots in terms of adaptability, maneuverability, and safety. Unfortunately, the soft and flexible materials used in their construction impose intrinsic limitations on soft robots, such as low actuation speeds and low output forces. Nature offers multiple examples where highly flexible organisms exploit mechanical instabilities to store and rapidly release energy.

The Influence of Airway Closure Technique for Right Pneumonectomy on Wall Tension During Positive Pressure Ventilation: An Experimental Study.

Bronchopleural fistula (BPF) remains a significant source of morbidity and mortality after right pneumonectomy (RPN). Postoperative mechanical ventilation represents a primary risk factor for BPF. We undertook an experiment to determine the influence of airway diameter on suture line tension during mechanical ventilation after RPN.

Engineered protein-based functional nanopatterned materials for bio-optical devices.

The development of new active biocompatible materials and devices is a current need for their implementation in multiple fields, including the fabrication of implantable devices for biomedical applications and sustainable devices for bio-optics and bio-optoelectronics. This paper describes a simple strategy to use designed proteins to develop protein-based functional materials. Using simple proteins as self-assembling building blocks as a platform for the fabrication of new optically active materials takes previous work one step further towards the design of materials with defined structures and functions using naturally occurring protein materials, such as silk.

Simultaneous electrophysiological recording and self-powered biosignal monitoring using epidermal, nanotexturized, triboelectronic devices.

The fabrication of multifunctional epidermal electronic devices capable of efficiently reading electrophysiological signals and converting low-amplitude mechanical signals into electric outputs promises to pave the way towards the development of self-powered wearable sensors, smart consumer electronics, and human-machine interfaces. This article describes the scalable and cost-effective fabrication of epidermal, nanotexturized, triboelectronic devices (EnTDs). EnTDs can be conformably worn on the skin and efficiently monitor electrophysiological signals, temperature, and hydration levels.

Editorial for Special Issue on Flexible Electronics: Fabrication and Ubiquitous Integration.

Based on the premise "anything thin is flexible", the field of flexible electronics has been fueled from the ever-evolving advances in thin-film materials and devices. [..

Rapid Fabrication of Epidermal Paper-Based Electronic Devices Using Razor Printing.

This work describes the use of a benchtop razor printer to fabricate epidermal paper-based electronic devices (EPEDs). This fabrication technique is simple, low-cost, and compatible with scalable manufacturing processes. EPEDs are fabricated using paper substrates rendered omniphobic by their cost-effective silanization with fluoroalkyl trichlorosilanes, making them inexpensive, water-resistant, and mechanically compliant with human skin.

Wearable and Implantable Epidermal Paper-Based Electronics.

Traditional manufacturing methods and materials used to fabricate epidermal electronics for physiological monitoring, transdermal stimulation, and therapeutics are complex and expensive, preventing their adoption as single-use medical devices. This work describes the fabrication of epidermal, paper-based electronic devices (EPEDs) for wearable and implantable applications by combining the spray-based deposition of silanizing agents, highly conductive nanoparticles, and encapsulating polymers with laser micromachining. EPEDs are inexpensive, stretchable, easy to apply, and disposable by burning.

Portable and power-free serodiagnosis of Chagas disease using magnetic levitating microbeads.

This work describes the detection of anti-T. cruzi antibodies in whole blood solutions using magnetic levitating microbeads (MLμBs). This simple diagnostic method can be easily performed by minimally trained personnel using an inexpensive and portable magnetic stage that requires no electricity.

Early detection and monitoring of chronic wounds using low-cost, omniphobic paper-based smart bandages.

The growing socio-economic burden of chronic skin wounds requires the development of new automated and non-invasive analytical systems capable of wirelessly monitoring wound status. This work describes the low-cost fabrication of single-use, omniphobic paper-based smart bandages (OPSBs) designed to monitor the status of open chronic wounds and to detect the formation of pressure ulcers. OPSBs are lightweight, flexible, breathable, easy to apply, and disposable by burning.

Roll-to-Roll Nanoforming of Metals Using Laser-Induced Superplasticity.

This Letter describes a low-cost, scalable nanomanufacturing process that enables the continuous forming of thin metallic layers with nanoscale accuracy using roll-to-roll, laser-induced superplasticity (R2RLIS). R2RLIS uses a laser shock to induce the ultrahigh-strain-rate deformation of metallic films at room temperature into low-cost polymeric nanomolds, independently of the original grain size of the metal. This simple and inexpensive nanoforming method does not require access to cleanrooms and associated facilities, and can be easily implemented on conventional CO lasers, enabling laser systems commonly used for rapid prototyping or industrial cutting and engraving to fabricate uniform and three-dimensional crystalline metallic nanostructures over large areas.

Fabrication of Silicon Nanobelts and Nanopillars by Soft Lithography for Hydrophobic and Hydrophilic Photonic Surfaces.

Soft lithography allows for the simple and low-cost fabrication of nanopatterns with different shapes and sizes over large areas. However, the resolution and the aspect ratio of the nanostructures fabricated by soft lithography are limited by the depth and the physical properties of the stamp. In this work, silicon nanobelts and nanostructures were achieved by combining soft nanolithography patterning with optimized reactive ion etching (RIE) in silicon.

Miniature objective lens with variable focus for confocal endomicroscopy.

Spectrally encoded confocal microscopy (SECM) is a reflectance confocal microscopy technology that can rapidly image large areas of luminal organs at microscopic resolution. One of the main challenges for large-area SECM imaging in vivo is maintaining the same imaging depth within the tissue when patient motion and tissue surface irregularity are present. In this paper, we report the development of a miniature vari-focal objective lens that can be used in an SECM endoscopic probe to conduct adaptive focusing and to maintain the same imaging depth during in vivo imaging.

Nanolithography. Large-scale nanoshaping of ultrasmooth 3D crystalline metallic structures.

We report a low-cost, high-throughput benchtop method that enables thin layers of metal to be shaped with nanoscale precision by generating ultrahigh-strain-rate deformations. Laser shock imprinting can create three-dimensional crystalline metallic structures as small as 10 nanometers with ultrasmooth surfaces at ambient conditions. This technique enables the successful fabrications of large-area, uniform nanopatterns with aspect ratios as high as 5 for plasmonic and sensing applications, as well as mechanically strengthened nanostructures and metal-graphene hybrid nanodevices.

Nanoskiving core-shell nanowires: a new fabrication method for nano-optics.

This paper describes the fabrication of functional optical devices by sectioning quantum-dot-in-nanowires systems with predefined lengths and orientations. This fabrication process requires only two steps, embedding the nanowires in epoxy and using an ultramicrotome to section them across their axis ("nanoskiving"). This work demonstrates the combination of the following four capabilities: (i) the control of the length of the nanowire sections at the nanometer scale; (ii) the ability to process the nanowires after cutting using wet etching; (iii) the possibility of modifying the geometry of the wire by varying the sectioning angle; and (iv) the generation of as many as 120 consecutive slabs bearing nanowires that have uniform size and approximately reproducible lateral patterns and that can subsequently be transferred to different substrates.

Rapid fabrication of pressure-driven open-channel microfluidic devices in omniphobic R(F) paper.

This paper describes the fabrication of pressure-driven, open-channel microfluidic systems with lateral dimensions of 45-300 microns carved in omniphobic paper using a craft-cutting tool. Vapor phase silanization with a fluorinated alkyltrichlorosilane renders paper omniphobic, but preserves its high gas permeability and mechanical properties. When sealed with tape, the carved channels form conduits capable of guiding liquid transport in the low-Reynolds number regime (i.

Miniature grating for spectrally-encoded endoscopy.

Spectrally-encoded endoscopy (SEE) is an ultraminiature endoscopy technology that acquires high-definition images of internal organs through a sub-mm endoscopic probe. In SEE, a grating at the tip of the imaging optics diffracts the broadband light into multiple beams, where each beam with a distinctive wavelength is illuminated on a unique transverse location of the tissue. By encoding one transverse coordinate with the wavelength, SEE can image a line of the tissue at a time without using any beam scanning devices.

Robotic tentacles with three-dimensional mobility based on flexible elastomers.

Soft robotic tentacles that move in three dimensions upon pressurization are fabricated by composing flexible elastomers with different tensile strengths using soft lithographic molding. These actuators are able to grip complex shapes and manipulate delicate objects. Embedding functional components into these actuators (for example, a needle for delivering fluid, a video camera, and a suction cup) extends their capabilities.

Separation of nanoparticles in aqueous multiphase systems through centrifugation.

This paper demonstrates the use of aqueous multiphase systems (MuPSs) as media for rate-zonal centrifugation to separate nanoparticles of different shapes and sizes. The properties of MuPSs do not change with time or during centrifugation; this stability facilitates sample collection after separation. A three-phase system demonstrates the separation of the reaction products (nanorods, nanospheres, and large particles) of a synthesis of gold nanorods, and enriches the nanorods from 48 to 99% in less than ten minutes using a benchtop centrifuge.

Nanopatterning of ferritin molecules and the controlled size reduction of their magnetic cores.

A nanopatterning method to deposit ferritin proteins with nanoscale accuracy over large areas is reported. Selective deposition is driven by the electrostatic interactions existing between the proteins and nanoscale features. Upon deposition, the protein shell can be removed by heating the patterns in an oxygen atmosphere.

Use of thin sectioning (nanoskiving) to fabricate nanostructures for electronic and optical applications.

This Review discusses nanoskiving--a simple and inexpensive method of nanofabrication, which minimizes requirements for access to cleanrooms and associated facilities, and which makes it possible to fabricate nanostructures from materials, and of geometries, to which more familiar methods of nanofabrication are not applicable. Nanoskiving requires three steps: 1) deposition of a metallic, semiconducting, ceramic, or polymeric thin film onto an epoxy substrate; 2) embedding this film in epoxy, to form an epoxy block, with the film as an inclusion; and 3) sectioning the epoxy block into slabs with an ultramicrotome. These slabs, which can be 30 nm-10 μm thick, contain nanostructures whose lateral dimensions are equal to the thicknesses of the embedded thin films.

Patterning the tips of optical fibers with metallic nanostructures using nanoskiving.

Convenient and inexpensive methods to pattern the facets of optical fibers with metallic nanostructures would enable many applications. This communication reports a method to generate and transfer arrays of metallic nanostructures to the cleaved facets of optical fibers. The process relies on nanoskiving, in which an ultramicrotome, equipped with a diamond knife, sections epoxy nanostructures coated with thin metallic films and embedded in a block of epoxy.

Survey of materials for nanoskiving and influence of the cutting process on the nanostructures produced.

This paper examines the factors that influence the quality of nanostructures fabricated by sectioning thin films with an ultramicrotome ("nanoskiving"). It surveys different materials (metals, ceramics, semiconductors, and conjugated polymers), deposition techniques (evaporation, sputter deposition, electroless deposition, chemical-vapor deposition, solution-phase synthesis, and spin-coating), and geometries (nanowires or two-dimensional arrays of rings and crescents). It then correlates the extent of fragmentation of the nanostructures with the composition of the thin films, the methods used to deposit them, and the parameters used for sectioning.

Silicon nanowire circuits fabricated by AFM oxidation nanolithography.

We report a top-down process for the fabrication of single-crystalline silicon nanowire circuits and devices. Local oxidation nanolithography is applied to define very narrow oxide masks on top of a silicon-on-insulator substrate. In a plasma etching, the nano-oxide mask generates a nanowire with a rectangular section.