Like any robot, soft robotic devices are built to manipulate their environment. By their very nature, however, soft robots are also affected by their surroundings. This is a strength that enables novel interactions, but since the robot is no longer rigid, it may lose track of its own conformational awareness; that is, it may be unable to determine its own state, or its configuration in space. Most animals manage this challenge with the physiological sense of proprioception, or positional awareness. A central challenge of soft robotics is to instill flexible autonomous devices with a similar self-awareness.

To address this challenge, researchers in Intelligent Materials and Systems at Helmholtz-Zentrum Dresden Rossendorf (HZDR) developed an ultra-thin electronic skin that senses magnetic fields. When incorporated in a soft magnetic robot, the skin can sense and report the intensity and direction of the local magnetic field. This can imbue the device with an understanding of where it is in relation to itself โ€“ whether and how far, for example, an arm is bent โ€“ and the device may in principle build its own sense of proprioception.

Collaborating with researchers from North Carolina State University and ยายืสำฦต, the team built and modeled a prototypical self-aware soft robot consisting of four folding arms. Experts in materials engineering at NCSU provided smart magnetic polymers that can soften and stiffen in response to light, while ยายืสำฦต Professor of Physics Ben Evans developed theoretical models to describe and predict the behavior of the device. Predictive models such as these are essential to developing a concept beyond the prototype stage. By understanding the physical laws governing an initial device, researchers can predict with confidence the behavior of an entire class of robot, enabling rapid optimization and development of subsequent generations.

This first report of a self-aware magnetic soft robot appeared in the June 24 issue of Advanced Materials.

The work was published March 31 in the journal Micromachines in collaboration with an interdisciplinary group of researchers from Weinberg Medical Physics, Purdue University School of Mechanical Engineering, and The Johns Hopkins Schools of Medicine and Engineering.

ABSTRACT: Soft, untethered microrobots composed of biocompatible materials for completing micromanipulation and drug delivery tasks in lab-on-a-chip and medical scenarios are currently being developed. Alginate holds significant potential in medical microrobotics due to its biocompatibility, biodegradability, and drug encapsulation capabilities. Here, we describe the synthesis of MANiACs- Magnetically Aligned Nanorods in Alginate Capsules – for use as untethered microrobotic surface tumblers, demonstrating magnetically guided lateral tumbling via rotating magnetic fields. MANiAC translation is demonstrated on tissue surfaces as well as inclined slopes. These alginate microrobots are capable of manipulating objects over millimeter-scale distances. Finally, we demonstrate payload release capabilities of MANiACs during translational tumbling motion.

Micromachines, 10(4), 230;

The work was published March 19 in ACS Nano in collaboration with Zhiren Luo and Chih-Hao Chang from the Department of Mechanical and Aerospace Engineering at North Carolina State University.

ABSTR

The findings are laid out in “,” an article available in the February issue of the peer-reviewed journal Nanoscale. The work was performed in collaboration with researchers at Weinberg Medical Physics, Inc.

As biophysicists dive deeper into single-molecule and single-cell experiments, it has become essential to develop mechanisms by which they can precisely and predictably manipulate microscopic matter. Nano- and microscale magnetic materials are an attractive option for doing so, since they allow non-contact interaction with the materials using macroscale magnetic fields.

In this manuscript, Evans and colleagues demonstrate magnetic control over a 5-micron-long gold and nickel rod. The configuration of the magnetic nickel component enables a novel type of motion that has never before been accomplished with magnetic micromaterials: the rod describes a double-cone rotation much like a kayaker’s paddle, and this motion allows the rod to “swim” through a fluid. The speed and direction of the swimming can be finely-controlled by the experimenters.

Evans and colleagues demonstrate that these magnetic microswimmers can be used to capture and transport a payload, such as a single cell. In addition, the kayaking motion can be used to mix viscous fluids on a microscale, which is a key barrier to the continued development of lab-on-a-chip medical diagnostic devices.

Evans has conducted extensive research on the use of magnetic forces on micromaterials. Earlier this year, t into how the use magnetic devices to control soft robots on its Science360 News website. 

​The article highlights the work by Evans and Joseph Tracy, associate professor of the Department of Materials Science and Engineering at N.C. State University, using magnetic fields to remotely manipulate microparticle chains embedded in soft robotic devices. 

Soft robotics is a relatively new field in which robotic devices are composed of flexible elements rather than rigid components. These new structures may enable new behaviors, such as novel forms of locomotion, actively-reconfigurable surfaces, or access to challenging terrain.

The current manuscript detailing the research builds on previous work by Evans in magnetically-actuated biomimetic cilia to develop new macroscopic magnetic devices which may be controlled with an external magnetic field. In these devices, magnetic microparticles are assembled into continuous magnetic chains within a polymer matrix, and these chains result in enhanced magnetic control over the materials.

Tracy and his team developed the novel magnetic materials and devices presented in the manuscript, and Evans applied the theoretical model to describe their performance and developed a new figure of merit for magnetic actuators which will be useful in accelerating progress in the field of magnetic soft robotics. 

Titled  the manuscript was published March 28 in ACS Applied Materials and Interfaces.

The research will be highlighted during the opening keynote address to be held at ยายืสำฦต on March 31 and April 1. 

Riley’s work investigated the feasibility of a novel magnetic drug-delivery vehicle which is capable of encapsulating pharmaceuticals to be released at a targeted location within the body. Specifically, Riley showed that the carrier was able to carry and release enough of a model drug to produce local, targeted drug concentrations equal to those delivered systemically with traditional chemotherapy. A targeted delivery system is advantageous since it minimizes dosages to healthy tissues, eliminating many of the side effects of traditional therapy.

Riley’s work was performed on collaboration with associate professor Ben Evans in the Department of Physics.

The March meeting of the American Physical Society is the largest annual international meeting of physicists, featuring more than 9,000 presentations from authors around the world.

Evans and his colleagues developed a new type of magnetic microsphere which provides tenfold more magnetic force than competing commercial products. The novel composition of the spheres results in a hundredfold reduction in the primary source of noise in certain types of medical diagnostic assays, potentially providing faster and earlier diagnosis of illness. In addition, the spheres are uniquely suited for the encapsulation and delivery of certain pharmaceuticals, suggesting utility in targeted chemotherapy treatments which may eliminate many of the side-effects of traditional chemotherapy.

This work was made possible by support from Faculty Research and Development, the Lumen Prize program, the ยายืสำฦต College Fellows, the Undergraduate Research Program and the Summer Undergraduate Research Experience.

The article is available online:

In this technique, microscopic magnetic particles are loaded with a chemotherapeutic agent and delivered directly to targeted tissues. Upon stimulation with magnetic fields, the particles simultaneously release the agent and heat the surrounding tissue. The heat makes nearby cells more susceptible to the pharmaceuticals, resulting in a highly-localized therapeutic effect.

Through his research, Evans seeks to better understand the physical mechanisms which underlie magnetic nanoparticle hyperthermia, as well as to produce new therapeutic materials which provide larger drug-carrying capacity and more efficient heating.

This proposal, “Advanced Instrumentation for Pre-Clinical Evaluation of Magnetic Nanoparticle Heating,” was written in collaboration with Drs. Nicole Levi and Ravi Singh of the Wake Forest University Comprehensive Cancer Center, who have expertise in biocompatible nanomaterials and in vivo delivery of encapsulated pharmaceuticals.

The work was conducted under the direction of Associate Professor of Physical Therapy Daryl Lawson and Assistant Professor of Engineering Chris Arena.

Also participating in the conference were Keeley Collins ’19 (Biochemistry), Sabrina Campelo ’18 (Physics), Zach O’Connor ’18 (Engineering Physics) and Associate Professor of Physics Ben Evans.

The meeting of the Biomedical Engineering Society highlighted “Career and Connections.” In addition to presenting research, students participated in panel discussions with local academics, innovators, and entrepreneurs, and networked with students and faculty from neighboring programs such as Biomedical Engineering at Duke University and the UNC/NCSU Joint Department of Biomedical Engineering.

Funding for student travel and registration was provided by a grant from the ยายืสำฦต Undergraduate Research Program.

Junior Matt Bausch, a double major in physics and finance, presented “The effect of inter-particle interactions on heating efficiency in magnetic nanoparticle hyperthermia: an experimental model,” which describes his contributions to the development of hyperthermia therapeutics, a new, drug-free therapy for the treatment of cancer. Bausch’s work seeks to understand the physical mechanisms underlying remote heating of magnetic nanoparticles, to better inform the design of future therapeutics.

Junior Aaron Neaves (Chemistry, BS) presented his work on an actuatable array of microscopic ciliary structures. This work, “High-density, high aspect ratio silicone post arrays for magneto-optical biosensing and targeted cell capture,” may lead to the development of more rapid or more sensitive assays for medical diagnostics.

In “High-magnetization silicone microbeads with low autofluorescence for biotech applications,” sophomore David Han (Engineering Physics, BS) demonstrated the production of a novel magnetic microsphere which represents a significant advance over currently available products. This sphere may be incorporated into existing diagnostic products to improve speed or sensitivity.

Also in attendance were associate professor Ben Evans and junior chemistry major Tom Riley. Riley has begun work on exploring the capability of the lab’s magnetic microspheres to absorb, deliver, and release a drug upon magnetic stimulation.