Ionic polymer‐metal composites as multifunctional materials

Abstract

This paper presents a description and a set of experimental results on Ionic Polymer‐Metal Composites (IPMC's) as dynamic sensors, transducers, and actuators. Strips of IPMC can exhibit large dynamic deformation if placed in a time‐varying electric field of the order of 10's of volts/mm. Conversely, dynamic deformation and flexing of such ionic polymers produces dynamic electric fields that closely follow the form of the electric signal. The underlying principle of such a mechanoelectric effect in IPMC's can be explained by the linear irreversible thermodynamics in which ion and solvent transport are the fluxes and electric field and solvent pressure gradient are the forces. Important parameters include the material conductance and the solvent permeability. The dynamic sensing, transduction, and actuation responses of a strip of IPMC under an impact‐type loading is also discussed. When a cantilever strip of IPMC is flipped, a damped oscillatory electric response is produced across a pair of electrodes placed at the cantilever of the strip, which is highly repeatable with a broad frequency range above 104 Hz. Such direct mechanoelectric responses of IMPC's are related to the endo‐ionic mobility due to stresses imposed. Imposition of a finite solvent flux without allowing a current flux causes the material to create a certain conjugate electric field that can be dynamically monitored and measured. IPMC's are shown to be highly capacitive at low frequencies while they are highly resistive under high frequency excitations. IN a sending mode, IPMC strips can also sense chemical environments and humidity. These types of sensors/transducers/actuators conceivably can replace piezoresistive and piezoelectric sensors with just one sensor for broad ranges of frequencies.

Influence of ionic liquid concentration on the electromechanical performance of ionic electroactive polymer actuators

“…Recently, electroactive polymers have received immense attention and interest from the materials community because of their applicability to actuators, sensors and haptics [1][2][3]. Electroactive polymers are soft and lightweight; hence, enable realization of biomimetic and microrobotic devices.…”

A fish robot driven by piezoceramic actuators and a miniaturized power supply

“…Free-swimming test After determining the optimum frequency for the largest thrust force, we operated the fish robot at that frequency by means of the miniaturized power supply installed inside the body (Fig. 12), and we used equation (3) to measure the free-swimming speed. The test was conducted in a water tank with a diameter of about 2 m. …”

“…A representative polymer-based actuator is the ionic polymer-metal composite (IPMC), which can create a large deformation with the application of just a few volts [3]. However, because its actuation force is very limited, the actuation displacement is considerably reduced when the IPMC is under a preload in an application device.…”

Ionic Polymer-Metal Composite Artificial Muscles in Bio-Inspired Engineering Research: Underwater Propulsion

“…Due to the similarities with biological muscles, in terms of achievable stress and strain, EAPs have great potential to be used as actuators in bio-inspired robots, bio-medical devices, and micro/nano manipulation systems. Ionic polymer-metal composites (IPMCs) are an important category of ionic EAPs (Shahinpoor & Kim, 2001Shahinpoor et al, 2003;Kim et al, 2007;Nemat-Nasser & Li, 2000;Nemat-Nasser, 2002), which can work well under a low actuation voltage (1 to 2 Volts) in a sodium salt-water environment.…”