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Recently, actuating materials based on carbon nanotubes or graphene have been widely studied. However, present carbon-based actuating materials are mostly driven by a single stimulus (humidity, light, electricity, etc.), respectively, which means that the application conditions are limited. Here, a new kind of multiresponsive actuating material which can be driven by humidity, light, and electricity is proposed, so it can be used in various conditions. The fabrication is based on the simplest pencil-on-paper method, in which the pencil and paper are both low-cost and easily obtained daily materials. The actuation effect is more remarkable due to a dual-mode actuation mechanism, which leads to an ultralarge actuation (bending curvature up to 2.6 cm−1). Elaborately designed, the actuator can further exhibit a bidirectional bending actuation, which is a significant improvement compared with previous reported thermal actuators. What is more, a colorful biomimetic flower and a smart curtain are also fabricated, fully utilizing the printable characteristic of the paper and multiresponsive characteristic of the actuator. It is assumed that the newly designed actuating material has great potential in the fields of lab-on-paper devices, artificial muscles, robotics, biomimics, and smart household materials. [ABSTRACT FROM AUTHOR]

We report a novel biodegradable piezoelectric composite fabricated from paper and the piezoelectric salt, sodium potassium tartrate tetrahydrate (Rochelle salt, which we term PiezoSalt). The piezoelectric composite is non-toxic and is fabricated free of environmentally harmful solvents by impregnating PiezoSalt into a paper matrix through the crystallization of a concentrated PiezoSalt brine solution. The composite exhibits an effective piezoelectric constant between 3 and 25 pC N −1 , dielectric constant of 7, mass density of 625 kg m −3 , and a Young’s modulus between 7 and 8 GPa. When directly actuated, cm-scale cantilevers consisting of PiezoSalt paper produced clearly audible sound waves, illustrating one potential application. PiezoSalt paper composite provides a scalable, high throughput approach for biodegradable sensors and transducers with unsurpassed environmentally friendly processing. [ABSTRACT FROM AUTHOR]

This paper describes the design and fabrication of electrically controlled paper actuators that operate based on the dimensional changes that occur in paper when the moisture absorbed on the surface of the cellulose fibers changes. These actuators are called 'Hygroexpansive Electrothermal Paper Actuators' (HEPAs). The actuators are made from paper, conducting polymer, and adhesive tape. They are lightweight, inexpensive, and can be fabricated using simple printing techniques. The central element of the HEPAs is a porous conducting path (used to provide electrothermal heating) that changes the moisture content of the paper and causes actuation. This conducting path is made by embedding a conducting polymer (PEDOT:PSS) within the paper, and thus making a paper/polymer composite that retains the porosity and hydrophilicity of paper. Different types of HEPAs (straight, precurved, and creased) achieved different types of motions (e.g., bending motion, accordion type motion). A theoretical model for their behavior is proposed. These actuators have been used for the manipulation of liquids and for the fabrication of an optical shutter. [ABSTRACT FROM AUTHOR]

In this work, the fabrication of Rochelle salt based piezoelectric structures is illustrated. Structures composed of paper and Rochelle salt are easily manufactured using simple processes. Both manufacturing and the material itself are environmental friendly. Additionally Rochelle salt is biocompatible. In the paradigm of a cleaner piezoelectric technology, the fabrication of active sensing or actuating devices is developed. Thus processing method, material and piezoelectric properties have been studied: (1) pure crystals are used as acoustic actuator, (2) properties of paper impregnated with Rochelle salt are detailed, (3) charge generation is demonstrated on the impregnated material. Actuating and sensing devices are reported in order to highlight the potential of this green piezoelectric material. [ABSTRACT FROM AUTHOR]

Abstract: Carbon nanotube papers have many potential applications from actuators to electrodes. Cross-linked papers with embedded nanoparticles are now being investigated for use in these applications. Here we report on the development of piezoelectric multi-walled carbon nanotube paper. The piezoelectric effect of the paper was enhanced by four orders of magnitude by embedding zinc oxide nanoparticles into the carbon nanotube network, resulting in a simple method for producing flexible piezoelectric carbon nanotube paper. [Copyright &y& Elsevier]

Abstract  In an earlier work we reported the discovery of cellulose as a smart material that can be used in sensors and actuators. While the cellulose-based Electro-Active Paper (EAPap) actuator has many merits – lightweight, dry condition, biodegradability, sustainability, large displacement output and low actuation voltage – its performance is sensitive to humidity. We report here on an EAPap made with a cellulose and sodium alginate that produces its maximum displacement at a lower humidity level than the earlier one. To fabricate this EAPap, we dissolved cellulose fibers into a aqueous solution of NaOH/urea. Sodium alginate (0, 5 or 10% by weight) was then added to this cellulose solution. The solution was cast into a sheet and hydrolyzed to form a wet cellulose-sodium alginate blend film. After drying, a bending EAPap actuator was made by depositing thin gold electrodes on both sides of it. The performance of the EAPap actuator was then evaluated in terms of free displacement and blocked force with respect to the actuation frequency, activation voltage and content of sodium alginate. The actuation principle is also discussed. [ABSTRACT FROM AUTHOR]

Most of conventional actuators have only actuation functions, lacking in real‐time sensing signal feedback. In article number 1806057, Luzhuo Chen and co‐workers report a graphene‐based actuator with integrated‐sensing functions. The robot hand based on the actuator can not only manipulate an object, but also sense every actuation state. This work will open new application fields in integrated‐multifunctional devices. [ABSTRACT FROM AUTHOR]

Flexible actuators have important applications in artificial muscles, robotics, optical devices, and so on. However, most of the conventional actuators have only actuation function, lacking in real‐time sensing signal feedbacks. Here, to break the limitation and add functionality in conventional actuators, a graphene‐based actuator with integrated‐sensing function is reported, which avoids the dependence on image post‐processing for actuation detection and realizes real‐time measurement of the shape‐deformation amplitudes of the actuator. The actuator is able to show a large bending actuation (curvature of 1.1 cm−1) based on a dual‐mode actuation mechanism when it is driven by near infrared light. Meanwhile, the relative resistance change of the actuator is −17.5%. The sensing function is attributed to piezoresistivity and thermoresistivity of the reduced graphene oxide and paper composite. This actuator can be used as a strain sensor to monitor human motions. A smart gripper based on the actuators demonstrates perfect integration of the actuating and sensing functions, which can not only grasp and release an object, but also sense every actuation state of the actuator. The developed integrated‐sensing actuator is hopeful to open new application fields in soft robotics, artificial muscles, flexible wearable devices, and other integrated‐multifunctional devices. A graphene‐based actuator with integrated‐sensing function is developed. It realizes real‐time measurements of the shape deformation of the actuator. A smart gripper based on the actuator demonstrates perfect integration of actuating and sensing functions. It can not only grasp and release an object, but also sense every actuation state of the actuator. [ABSTRACT FROM AUTHOR]

G. M. Whitesides and co‐workers describe, on page 2446, the design and fabrication of electrically controlled paper actuators made from paper, conducting polymer, and adhesive tape. The central element of the actuators is a porous conducting path providing electrothermal heating that changes the moisture content of the paper and causes actuation. These simple and inexpensive devices can achieve different types of motion such as bending and accordion‐type motion. [ABSTRACT FROM AUTHOR]