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This work presents a unique approach to the design, fabrication, and characterization of paper-based origami robotic systems consisting of stackable pneumatic actuators. These paper-based actuators (PBAs) use materials with high elastic modulus-to-mass ratios, accordion-like structures, and direct coupling with pneumatic pressure for extension and bending. The study contributes to the scientific and engineering understanding of foldable components under applied pneumatic pressure by constructing stretchable and flexible structures with intrinsically nonstretchable materials. Experiments showed that a PBA possesses a power-to-mass ratio greater than 80 W/kg, which is more than four times that of human muscle. This work also illustrates the stackability and functionality of PBAs by two prototypes: a parallel manipulator and a legged locomotor. The manipulator consisting of an array of PBAs can bend in a specific direction with the corresponding actuator inflated. In addition, the stacked actuators in the manipulator can rotate in opposite directions to compensate for relative rotation at the ends of each actuator to work in parallel and manipulate the platform. The locomotor rotates the PBAs to apply and release contact between the feet and the ground. Furthermore, a numerical model developed in this work predicts the mechanical performance of these inflatable actuators as a function of dimensional specifications and folding patterns. Overall, we use stacked origami actuators to implement functionalities of manipulation, gripping, and locomotion as conventional robotic systems. Future origami robots made of paper-like materials may be suitable for single use in contaminated or unstructured environments or low-cost educational materials.

This article describes a process of fabricating highly porous paper from cellulosic fibers and carbon black (CB) with tunable conductivity. By embossing such paper, its porosity decreases while its conductivity increases. Tuning the porosity of composite paper alters the magnitude and trend of conductivity over a spectrum of concentrations of conductive particles. The largest increase in conductivity from 8.38 × 10-6 to 2.5 × 10-3 S/m by a factor of ∼300 occurred at a percolation threshold of 3.8 wt % (or 0.36 vol %) with the composite paper plastically compressed by 410 MPa, which caused a decrease of porosity from 88% to 42% on average. Our composite paper showed stable piezoresistive responses within a broad pressure range from 1 kPa up to 5.5 MPa for 800 cycles. The piezoresistive sensitivities of the composite paper were dependent on concentration and decreased with pressure. Composite paper with 7.5 wt % CB had sensitivities of -0.514 kPa-1 over applied pressures ranging from 1 to 50 kPa and -0.215 kPa-1 from 1 to 250 kPa. This piezoresistive paper with embossed patterns enabled touch sensing and detection of damage from darts and punches. Understanding the percolation behavior of three-phase composites (cellulosic fibers/conductive particles/air) and their response to damage, pressure, and processing conditions has the potential to enable scalable applications in prosthetics and robotics, haptic feedback, or structural health monitoring on expansive surfaces of buildings and vehicles.

As a material, cellulose/paper has attracted significant attention for its fibrous and bendable properties. Paper is a renewable resource with the most common forms coming from trees. This brief article describes efforts to create electronics "on" and "in" paper. Examples of electronics on paper include touch sensors and cold plasma-based sanitizers. The skin-like touch sensors use capacitance and patterned resistive networks for passive, scalable sensing with a reduced number of interconnects. When touched or wetted with water, the interdigitated electrodes in the resistive networks detect significant changes in electrical impedance. The plasma generators with layered and patterned sheets of paper use a simple and flexible format for dielectric barrier discharge to create atmospheric plasma without an applied vacuum. Examples of electronics in paper include sheets with tunable electrical conductivity and piezoresistive force sensors, along with functionalized paper-based electrodes capable of detecting small proteins and clinically relevant biomarkers. These papertronic devices have the potential to supply multi-functionality to new forms of smart bandages, skin-like sensing, food packaging, and robotic sensing and actuation.

This paper presents the design, characterization, and experimental evaluation of a wireless capacitive pressure sensor embedded within a rotating workroll of a microrolling machine for monitoring the production of micrometer-scaled texture on thin metallic workpiece. The sensor converts the spatial and temporal variations of pressure across the interface between the roll and workpiece into capacitance values, thereby experimentally establishing a quantitative correlation between the online measurement and the geometric features being formed on the workpiece, in real time. Analytical and numerical models have been developed to guide the design of the sensor to maximize the capacitance output while satisfying the space constraint. A sensitivity matrix linking the measured capacitance with pressure distribution has been established through numerical analysis. Simulation and experiments confirmed the effectiveness of the embedded sensor in enabling intelligent microrolling.

Microrolling is an advanced manufacturing process for the mass production of miniaturized components. At the micrometer scale, small deviation in material thickness or roll misalignment can lead to significant variation of the pressure distribution across the product, resulting in dimensional inaccuracy of the imprinted texture. To address this problem, an embedded sensing system has been developed to monitor in situ the spatial pressure distribution across the tool–workpiece interface. A key element of the sensing system is a pressure reconstruction algorithm, which determines the deformation across the roll structure from a limited number of sensing points, and converts the data subsequently into pressure distribution across the workpiece. This paper investigates how backprojection and interpolation can be integrated synergistically to improve the accuracy and robustness of pressure reconstruction. Specifically, interpolation is performed as a pre-possessing step to increase the resolution in capacitance variation estimation and improve the robustness of back-projection in solving the inverse problem of capacitance–pressure conversion. Experimental study confirmed the performance of the developed method.

This article presents a sensor for detecting the distribution of forces on a surface. The device with nine buttons consisted of an elastomer-based layer as a touch interface resting on a substrate of patterned metallized paper. The elastomer-based layer included a three-by-three array of deformable, hemispherical elements/reliefs, facing down toward an array of interdigitated capacitive sensing units on patterned metallized paper. Each hemispherical element is 20 mm in diameter and 8 mm in height. When a user applied pressure to the elastomer-based layer, the contact area between the hemispherical elements and the interdigitated capacitive sensing units increased with the deformation of the hemispherical elements. To enhance the sensitivity of the sensors, embedded particles of hydrogel in the elastomer-based layer increased the measured electrical responses. The measured capacitance increased because the effective dielectric permittivity of the hydrogel was greater than that of air. Electromechanical characterization verified that the hydrogel-filled elastomer was more sensitive to force at a low range of loads (23.4 pF/N) than elastomer alone without embedded hydrogel (3.4 pF/N), as the hydrogel reduced the effective elastic modulus of the composite material by a factor of seven. A simple demonstration suggests that the force-sensing array has the potential to contribute to wearable and soft robotic devices.

Microrolling is an advanced manufacturing process for the mass production of miniaturized components. At the micrometer scale, small deviation in material thickness or roll misalignment may significantly alter pressure distribution across the product, resulting in variations in the imprinted texture dimension. An embedded sensing method has been developed to monitor the pressure distribution across the workpiece. A key component of the sensing method is a pressure retrieving algorithm that determines deformation across the roll structure from a limited number of sensing points and converts the data subsequently into pressure distribution, based on the theories of interpolation and back-projection. In this paper, a combination of interpolation (Bezier Curve, Thin Plate Spline, and Kriging) and Tikhonov regularization have been used to resolve the inverse problem.

This paper will review the origins and state of the art in paper-based electronics, suggesting the stage is set for future promising applications. Current interest in paper-based electronics can trace its roots to recent developments in paper-based microfluidics. With a need to improve the reliability and sensitivity of paperbased microfluidics for certain tasks, there were natural efforts to begin embedding sensing electrodes into microfluidic devices. Recognizing the general benefits of paper as an advanced material (e.g., its environmental friendliness, bendable nature, and low cost), efforts in paper-based electronics also began to take a life of their own with demonstrations of transistors, batteries and devices for energy storage, energy harvesting, sensors to improve situational awareness, acoustics, and displays. The state-of-the-art paper-based electronic devices have benefited and will continue to profit from technologies for printing and transferring electronic functionality onto the surfaces of paper-based substrates. Nonetheless, the authors suggest that many future promising applications will go beyond using paper as a carrier/substrate for electronic components to explore tuning of the electrical, mechanical, and chemical properties of the paper itself. With these technical advances, paper-based electronics will move closer to economically viable killer applications.

The paper focused on the effect of tool edge preparation of indexable carbide insert on cutting temperature, force and tool wear. The initial wear experiments were carried out to measure flank wear and two criteria to evaluate the effect of tool edge preparation were proposed. The cutting temperature measurement utilized tool-work thermocouple and revealed that the cutting temperature of honed insert was lower. The cutting force measurement with a strain gauge dynamometer showed that tangential cutting force Fz, feed force Fx would be increased and radius force Fy would be decreased after tool edge preparation.