Ionic Polymer-Metal Composites (IPMC) are common soft actuators that are Nafion® based and plated with a conductive metal, such as platinum, gold, or palladium. Nafion® is available in three forms: sheets, pellets, and water dispersion. Nafion® sheets can be cut to the desired dimensions and are best for rectangular IPMCs. However, the user is not able to change the thickness of these sheets by stacking and melting because Nafion® does not melt. A solution to this is Nafion® pellets, which can melt. These can be used for extrusion and injection molding. Though Nafion® pellets can be melted, they are difficult to work with, making the process quite challenging to master. The last form is Nafion® Water Dispersion, which can be used for casting. Casting can produce the desired thickness, but it does not solve the problem of achieving complex contours. The current methods of fabrication do not allow for complex shapes and structures. To solve this problem, two methods are presented: painting and printing. The painting method uses Nafion® Water Dispersion, an airbrush, and vinyl stencils. The stencils can be made into any shape with detailed edges. The printing method uses Nafion® pellets that are extruded into filaments and a commercially available 3D printer. The models are drawn in a Computer-Aided Drawing (CAD) program, such as SolidWorks. The produced Nafion® membranes will be compared with a commercial Nafion® membrane through a variety of tests, including Fourier Transform Infrared Spectroscopy, Scanning Electron Microscope, Thermogravimetric Analysis, Dynamic Mechanical Analysis, and Optical Microscope.
The blended ion exchange membrane between Nafion and Polyimide (PI) was used for fabrication of the ionic polymer–metal composite (IPMC) not only to redeem inherent drawbacks of Nafion such as high cost or environment-unfriendliness but also to enhance mechanical properties of Nafion. PI solution was blended in Nafion solution by a volume ratio and membranes were prepared through solution casting method. The prepared blended Nafion membranes can be fabricated IPMCs with electroless plating of platinum electrode onto its surface. The surface resistance of all prepared IPMCs is measured through 2-point probe. This study investigated the chemical structure and mechanical properties of prepared blended membranes. Moreover, we characterized the cross-section morphology and studied the electromechanical performances (displacement and blocking force) of prepared IPMC actuators. The prepared IPMC actuators with blended Nafion membranes were demonstrated comparable electromechanical performance by significantly reducing the content of Nafion.
The multiple-shape-memory ionic polymer-metal composite (MSM-IPMC) actuator can demonstrate complex 3D
deformation. The MSM-IPMC have two characteristics, which are the electro-mechanical actuation effect and the
thermal-mechanical shape memory effect. The bending, twisting, and oscillating motions of the actuator could be
controlled simultaneously or separately by means of thermal-mechanical and electro-mechanical transactions. In our
study, we theoretically modelled and experimentally investigated the MSM-IPMC. We proposed a new physical
principle to explain the shape memory behavior. A theoretical model of the multiple shape memory effect of MSMIPMC
was developed. It is based on the assumption that the multiple shape memory effect is caused by the thermal stress
and each individual Young’s modulus is ‘memorized’ during the previous programming process. As the MSM-IPMC
was reheated to each temperature, the corresponding thermal stress was applied on the MSM-IPMC, and the Young’s
modulus was recovered, which result in the shape recovery of the MSM-IPMC. To verify the model, a MSM-IPMC
sample was prepared. Experimental tests of MSM-IPMC were conducted. By comparing the simulation results and the
experimental results, both results have a good agreement. The current study is beneficial for the better understanding of
the underlying physics of MSM-IPMC.
Artificial muscle (AM) technology is an excellent candidate for creating cilia-based structures for bio-inspired locomotion, maneuvering, and acoustic systems. We developed an AM based cilia fiber which are soft, flexible, easily shaped and low power consumption. The developed cilium has a diameter of around 200 µm and prepared through polymer injection technique. Nafion was used for base polymer for cilia and fabricated IPMCs via platinum electroless plating process. The prepared cilia were characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. The 2 point probe was conducted to measure electrode surface resistance of prepared IPMCs. We further characterized the cross-sectional morphology and studied the electromechanical performances (displacement and blocking force) of the prepared IPMC actuators. Also we created prototype mm-sized AM fiber cilia array (3x20) and tested the actuation of AM cilia fiber under external electric field.
Ionic Polymer-Metal Composites (IPMC) are useful actuators because of their ability to be fabricated in different shapes and move in various ways. However, the process to produce an IPMC is complicated and takes a few days. To make it possible to mass produce in any desired shape, the fabrication process must be updated. Presented here is a new way of producing the Nafion® base through a spraying method, then the electrode will be plated with spraying method as well. To verify that this method of fabrication produces a Nafion® sample similar to that which is commercially available, a sample that was made using spraying method and N117 purchased from DuPont™ were tested for various characteristics and compared.
The blended ion exchange membrane between Nafion and ethylene vinyl alcohol (EVOH) was used for fabrication of the ionic polymer–metal composite (IPMC) to redeem inherent drawbacks of Nafion such as high cost or environment-unfriendliness. EVOH solution was blended in Nafion solution by a volume ratio of 15 and 30 % membranes were prepared through solution casting method. The prepared blended Nafion membranes can be fabricated IPMCs with deposition of platinum electrode onto its surface without crack or delamination. The surface resistance of all prepared IPMCs is measured through 2 point probe. This study investigated the chemical structure and thermal properties of prepared membranes. Moreover, we characterized the cross-section morphology and studied the electromechanical performances (displacement and blocking force) of prepared IPMC actuators. The IPMC actuators with proposed blended Nafion membranes were demonstrated comparable electromechanical performance by significantly reducing the content of Nafion.
Variable stiffness features can contribute to many engineering applications ranging from robotic joints to shock and vibration mitigation. In addition, variable stiffness can be used in the tactile feedback to provide the sense of touch to the user. A key component in the proposed device is the Biased Magnetorheological Elastomer (B-MRE) where iron particles within the elastomer compound develop a dipole interaction energy. A novel feature of this device is to introduce a field induced shear modulus bias via a permanent magnet which provides an offset with a current input to the electromagnetic control coil to change the compliance or modulus of a base elastomer in both directions (softer or harder). The B-MRE units can lead to the design of a variable stiffness surface. In this preliminary work, both computational and experimental results of the B-MRE are presented along with a preliminary design of the programmable variable stiffness surface design.