Design-based modeling of magnetically actuated soft diaphragm materials

Abstract

Magnetic polymer composites (MPC) have shown promise for emerging biomedical applications such as lab-on-a-chip and implantable drug delivery. These soft material actuators are capable of fast response, large deformation and wireless actuation. Existing MPC modeling approaches are computationally expensive and unsuitable for rapid design prototyping and real-time control applications. This paper proposes a macro-scale 1-DOF model capable of predicting force and displacement of an MPC diaphragm actuator. Model validation confirmed both blocked force and displacement can be accurately predicted in a variety of working conditions i.e. different magnetic field strengths, static/dynamic fields, and gap distances. The contribution of this work includes a comprehensive experimental investigation of a macro-scale diaphragm actuator (in terms of both force and displacement); the derivation and validation of a new phenomenological model to describe MPC actuation; and insights into the proposed model's design-based functionality i.e. scalability and generalizability in terms of magnetic filler concentration and diaphragm diameter. Due to the lumped element modeling approach, the proposed model can be adapted to alternative actuator configurations, and thus presents a useful tool for design, control and simulation of novel MPC applications.

Nonlinear displacement control of magnetic material actuators

“…The size, shape and material of the magnetic filler particles affect the overall magnetic permeability of the sample. Additionally, increasing the magnetic filler concentration can increase overall magnetic permeability and improve diaphragm displacement [5,19]. Here, the weight concentration of the atomized iron magnetic filler was limited to 20 wt%.…”

“…The configuration of the MPC diaphragm actuator has been outlined in previous works [10,19]. The system, illustrated in figure 1, consists of an MPC diaphragm and single iron-core electromagnet.…”

“…The actuator response varies nonlinearly across the operating range because the equivalent mechanical and magnetic properties vary with displacement, i.e. DC/steady-state gain is not constant [19]. This nonlinear behavior may be linearized about multiple operating regions using gain scheduling.…”

“…A third order plant model was used to capture the transient and steady-state behavior of the MPC system at discrete operating points. Previous work revealed a first or second order model structure was not adequate [19]. The third order (Type 0) model is given by the following expression, where b is a constant and p 1−3 are plant poles…”

Acarid Suction Cup‐Inspired Rapid and Tunable Magnetic Adhesion

“…As a typical smart material, the magnetic polymer can deform completely within 500 ms under the magnetic field. [ 23 ] The MSC (radius is 20 mm and thickness is 1 mm) can actively grasp a load of 50 g (The electromagnet with a diameter of 80 mm and a height of 80 mm). To facilitate the design and manufacture of MSCs, we develop an experiment‐based mechanical model.…”