We report a novel partial dissolution strategy to liberate uniform cellulose nanofibers with diameter of 5-10 nm from macroscopic cellulose fibers and promote separation of nanofibers in an aqueous environment by forming water-soluble sodium carboxymethylcellulose (CMC) through heterogeneous sodium acetoxylation of cellulose. With the obtained cellulose nanofibers, we fabricated nanopapers which exhibit high optical transparency of 90.5% (@550 nm) with promising mechanical properties and high thermal stability. By directly depositing Ag nanowires on a wet nanofiber sheet, we fabricated a flexible transparent electrode with 86.5% (@550 nm) transparency and 26.2 Ω/sq sheet resistance (R). Meanwhile, we studied the magnetic properties of sputter deposited thin film of permalloy on nanopaper which exhibited a similar magnetic coercivity and a close saturation magnetization to conventional silicon dioxide-based permalloy.

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.

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In this work, we developed and fabricated a paper-based anisotropic magneto-resistive sensor using a sputtered permalloy (Ni81Fe19) thin film. To interpret the characteristics of the sensor, we proposed a computational model to capture the influence of the stochastic fiber network of the paper surface and to explain the physics behind the empirically observed difference in paper-based anisotropic magneto-resistance (AMR). Using the model, we verified two main empirical observations: (1) The stochastic fiber network of the paper substrate induces a shift of 45∘ in the AMR response of the paper-based Ni81Fe19 thin film compared to a Ni81Fe19 film on a smooth surface as long as the fibrous topography has not become buried. (2) The ratio of magnitudes of AMR peaks at different anisotropy angles and the inverted AMR peak at the 90∘-anisotropy angle are explained through the superposition of the responses of Ni81Fe19 inheriting the fibrous topography and smoother Ni81Fe19 on buried fibrous topographies. As for the sensitivity and reproducibility of the sensor signal, we obtained a maximum AMR peak of 0.4%, min-max sensitivity range of [0.17,0.26]%, average asymmetry of peak location of 2.7 kAnormalm within two consecutive magnetic loading cycles, and a deviation of 250–850 normalAnormalm of peak location across several anisotropy angles at a base resistance of ∼100 Ω. Last, we demonstrated the usability of the sensor in two educational application examples: a textbook clicker and interactive braille flashcards.

In the field of modern information technology, optoelectronics are being widely used, and play an increasingly important role. Meanwhile, the demand for more flexible circuit carriers is rapidly growing, since flexibility facilitates the realization of diverse functions and applications. As a potential candidate, transparent polymer substrates with a thickness of about a hundred micrometers by virtue of their low cost and sufficient flexibility are getting more attention. Thus, accomplishing an integration of optoelectronic components into polymer based flexible circuit systems increasingly is becoming an attractive research topic, which is of great significance for future information transmission and processing. We are committed to developing a new microchip bonding process to realize it. Taking into account the fact that most economical transparent polymer substrates can only be processed with restricted thermal loading, we designed a so-called optode instead of a widely adopted thermode. We employ UV-curing adhesives as bonding materials; accordingly, the optode is equipped with a UV irradiation source. An investigation of commercial optoelectronic components is conducted, in which their dimensions and structures are studied. While selecting appropriate transparent polymer substrates, we take their characteristics such as UV transmission degree, glass transition temperature, etc. as key criterions, and choose polyethylene terephthalate (PET) and polymethyl methacrylate (PMMA) as carrier materials. Besides bonding achieved through the use of adhesives cured by the optode, underfill is accordingly employed to enhance the reliability of the integration. We deposit electrical interconnects onto the polymeric substrate to be able to bring the optoelectronic components into electrical operation. In order to enlarge the optical coupling zone from component to substrate within the proximity of the adhesive or underfill, we employ transparent interconnects made of indium-tin-oxide. We present the results of the performance tests, including the contact resistances, mechanical tests and environmental tests.