High-Performance Polyvinyl Chloride Gel Artificial Muscle Actuator with Graphene Oxide and Plasticizer

A transparent and electroactive plasticized polyvinyl chloride (PVC) gel was investigated to use as a soft actuator for artificial muscle applications. PVC gels were prepared with varying plasticizer (dibutyl adipate, DBA) content. The prepared PVC gels were characterized using Fourier-transform infrared spectroscopy, thermogravimetric analysis, and dynamic mechanical analysis. The DBA content in the PVC gel was shown to have an inverse relationship with both the storage and loss modulus. The electromechanical performance of PVC gels was demonstrated for both single-layer and stacked multi-layer actuators. When voltage was applied to a single-layer actuator and then increased, the maximum displacement of PVC gels (for PVC/DBA ratios of 1:4, 1:6, and 1:8) was increased from 105.19, 123.67, and 135.55 µm (at 0.5 kV) to 140.93, 157.13, and 172.94 µm (at 1.0 kV) to 145.03, 191.34, and 212.84 µm (at 1.5 kV), respectively. The effects of graphene oxide (GO) addition in the PVC gel were also investigated. The inclusion of GO (0.1 wt.%) provided an approximate 20% enhancement of displacement and 41% increase in force production, and a 36% increase in power output for the PVC/GO gel over traditional plasticizer only PVC gel. The proposed PVC/GO gel actuator may have promising applications in artificial muscle, small mechanical devices, optics, and various opto-electro-mechanical devices due to its low-profile, transparency, and electrical response characteristics

Temperature compensated tactile sensing using MOSFET with P(VDF-TrFE)/BaTiO3 capacitor as extended gate

This work presents Poly(vinylidene fluoride – trifluoroethylene))/Barium Titanate (P(VDF-TrFE)-BT) nanocomposite based touch sensors tightly coupled with MOSFET devices in extended gate configuration. The P(VDF-TrFE)-BT nanocomposite exploits the distinct piezo and pyroelectric properties of P(VDF-TrFE) polymer matrix and BT fillers to suppress the temperature response when force and temperature are varied simultaneously. The reasons for this unique feature have been established through structural and electrical characterization of nanocomposite. The proposed touch sensor was tested over a wide range of force/pressure (0-4N)/(0-364 Pa) and temperature (26-70°C) with almost linear response. The sensitivity towards force/pressure and temperature sensor are 670 mV/N/7.36 mV/Pa and 15.34 mV/°C respectively. With this modified touch sensing capability, the proposed sensors will open new direction for tactile sensing in robotic applications

Overview effect of biodiesel storage on properties and characteristics

Abstract. Biofuels based on vegetable oils offer the advantage being a sustainable and environmen-tally attractive alternative to conventional petroleum based fuel. The key issue in using vegetable oil-based fuels is oxidation stability, stoichiometric point, bio-fuel composition, antioxidants on the degradation and much oxygen with comparing to diesel gas oil. This provides a critical review of current understanding of main factor in storage method which affecting the biodiesel properties and characteristics. In the quest for fulfill the industry specifications standard; the fuel should be stored in a clean, dry and dark environment. Water and sediment contamination are basically housekeep-ing issues for biodiesel. Degradation by oxidation yields products that may compromise fuel proper-ties, impair fuel quality and engine performance. The effect of storage method on the fuel properties and burning process in biodiesel fuel combustion will strongly affects the exhaust emissions

Converting water adsorption and capillary condensation in useable forces with simple porous inorganic thin films

This work reports an innovative humidity driven actuation concept based on Bangham effect using simple nanoporous sol-gel silica thin films as humidity responsive materials. Bilayer shaped actuators, consisting on a humidity-sensitive active nanostructured silica film deposited on a polymeric substrate (Kapton) were demonstrated as an original mean to convert water molecule adsorption and capillary condensation in useable mechanical work. Reversible silica surface energy modifications by water adsorption and the energy produced by the rigid silica film contraction, induced by water capillary condensation in mesopores, were finely controlled and used as the energy sources. The influence of the film nanostructure (microporosity, mesoporosity) and thickness, and of the polymeric support thickness, on the actuation force, on the movement speed, and on the amplitude of displacement are clearly evidenced and discussed. We show that the global mechanical response of such silica-based actuators can be easily adjusted to fabricate a humidity variation triggered tailor-made actuation systems. This first insight in hard ceramic stimulus responsive materials may open the door toward new generation of surface chemistry driven actuation systems.Comment: 17 pages, 7 figure

From Filter Paper to Functional Actuator by Poly(ionic liquid)-Modified Graphene Oxide

A commercially available membrane filter paper composed of mixed cellulose esters bearing typically an interconnected pore structure was transformed into a stimuli-responsive bilayer actuator by depositing a thin film of poly(ionic liquid)-modified graphene oxide sheets (GO-PIL) onto the filter paper. In acetone vapor, the as-synthesized bilayer actuator bent readily into multiple loops at a fast speed with the GO-PIL top film inwards. Upon pulling back into air the actuator recovered their original shape. The asymmetric swelling of the top GO-PIL film and the bottom porous filter paper towards organic vapor offers a favorably synergetic function to drive the actuation. The PIL polymer chains in the hybrid film were proven crucial to enhance the adhesion strength between the GO sheets and the adjacent filter paper to avoid interfacial delamination and thus improve force transfer. The overall construction allows a prolonged lifetime of the bilayer actuator under constant operation, especially when compared to that of the GO/filter paper bilayer actuator without PIL.Comment: 23 pages, 7 figure

Dual sensing-actuation artificial muscle based on polypyrrole-carbon nanotube composite

Dual sensing artificial muscles based on conducting polymer are faradaic motors driven by electrochemical reactions, which announce the development of proprioceptive devices. The applicability of different composites has been investigated with the aim to improve the performance. Addition of carbon nanotubes may reduce irreversible reactions. We present the testing of a dual sensing artificial muscle based on a conducting polymer and carbon nanotubes composite. Large bending motions (up to 127 degrees) in aqueous solution and simultaneously sensing abilities of the operation conditions are recorded. The sensing and actuation equations are derived for incorporation into a control system.The research was supported by European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No 641822

Materials selection and design of microelectrothermal bimaterial actuators

A common form of MEMS actuator is a thermally actuated bimaterial, which is easy to fabricate by surface micromachining and permits out of plane actuation, which is otherwise difficult to achieve. This paper presents an analytical framework for the design of such microelectrothermal bimaterial actuators. Mechanics relationships for a cantilever bimaterial strip subjected to a uniform temperature were applied to obtain expressions for performance metrics for the actuator, i.e., maximum work/volume, blocked (force) moment, and free-end (displacement) slope. Results from finite-element analysis and closed form relations agree well to within 1%. The optimal performance for a given pair of materials and the corresponding thickness ratio were determined. Contours of equal performance corresponding to commonly used substrates (e.g., Si, SiO2) were plotted in the domain of governing material properties (thermal expansion coefficient and Young's modulus) to identify candidate materials for further development. These results and the accompanying methodology provide a rational basis for comparing the suitability of "standard" materials for microelectrothermal actuators, as well as identifying materials that might be suitable for further research

Unconventional Uses of Microcantilevers as Chemical Sensors in Gas and Liquid Media

The use of microcantilevers as (bio)chemical sensors usually involves the application of a chemically sensitive layer. The coated device operates either in a static bending regime or in a dynamic flexural mode. While some of these coated devices may be operated successfully in both the static and the dynamic modes, others may suffer from certain shortcomings depending on the type of coating, the medium of operation and the sensing application. Such shortcomings include lack of selectivity and reversibility of the sensitive coating and a reduced quality factor due to the surrounding medium. In particular, the performance of microcantilevers excited in their standard out-of-plane dynamic mode drastically decreases in viscous liquid media. Moreover, the responses of coated cantilevers operating in the static bending mode are often difficult to interpret. To resolve these performance issues, the following emerging unconventional uses of microcantilevers are reviewed in this paper: (1) dynamic-mode operation without using a sensitive coating, (2) the use of in-plane vibration modes (both flexural and longitudinal) in liquid media, and (3) incorporation of viscoelastic effects in the coatings in the static mode of operation. The advantages and drawbacks of these atypical uses of microcantilevers for chemical sensing in gas and liquid environments are discussed