@article{clary_cantu_liu_evans_tracy_2024, title={Magnetic Reprogramming of Self-Assembled Hard-Magnetic Cilia}, ISSN={["2365-709X"]}, DOI={10.1002/admt.202302243}, abstractNote={Abstract Artificial magnetic cilia are hair‐like structures that can respond to magnetic fields. Using hard magnetic materials in magnetic cilia makes possible programming and reprogramming of the magnetization state and corresponding actuation behaviors. Hard‐magnetic cilia are fabricated through self‐assembly by solvent casting of a slurry of NdFeB microparticles dispersed in a solution of a thermoplastic polyurethane elastomer. These hard‐magnetic cilia are capable of attractive and repulsive responses to magnetic fields, determined by the remanent magnetization of the NdFeB microparticles. An array of cilia can be magnetically reprogrammed through immobilization in ice, applying a damped alternating magnetic field first to reduce the remanent magnetization, and then remagnetizing the cilia with a large field. This demagnetization process significantly improves the reprogrammability of the cilia array. Different responses to magnetic fields can be programmed, including spatially nonuniform behaviors. Reprogrammed hard‐magnetic cilia exhibit unique behaviors in rotating magnetic fields. After reprogramming the magnetization direction along the width of the cilia, rotation and torsion cause them to slowly coil and then quickly uncoil in a snapping behavior. Modeling the magnetic and elastic torques during actuation provides additional insights and aids the design of magnetic cilia actuators based on hard magnets.}, journal={ADVANCED MATERIALS TECHNOLOGIES}, author={Clary, Matthew R. and Cantu, Saarah N. and Liu, Jessica A. -C. and Evans, Benjamin A. and Tracy, Joseph B.}, year={2024}, month={Apr} }
 @article{ha_canon bermudez_liu_oliveros mata_evans_tracy_makarov_2021, title={Reconfigurable Magnetic Origami Actuators with On-Board Sensing for Guided Assembly}, volume={33}, ISSN={["1521-4095"]}, url={https://doi.org/10.1002/adma.202008751}, DOI={10.1002/adma.202008751}, abstractNote={AbstractOrigami utilizes orchestrated transformation of soft 2D structures into complex 3D architectures, mimicking shapes and functions found in nature. In contrast to origami in nature, synthetic origami lacks the ability to monitor the environment and correspondingly adjust its behavior. Here, magnetic origami actuators with capabilities to sense their orientation and displacement as well as detect their own magnetization state and readiness for supervised folding are designed, fabricated, and demonstrated. These origami actuators integrate photothermal heating and magnetic actuation by using composite thin films (≈60 µm thick) of shape‐memory polymers with embedded magnetic NdFeB microparticles. Mechanically compliant magnetic field sensors, known as magnetosensitive electronic skins, are laminated on the surface of the soft actuators. These ultrathin actuators accomplish sequential folding and recovery, with hinge locations programmed on the fly. Endowing mechanically active smart materials with cognition is an important step toward realizing intelligent, stimuli‐responsive structures.}, number={25}, journal={ADVANCED MATERIALS}, author={Ha, Minjeong and Canon Bermudez, Gilbert Santiago and Liu, Jessica A. -C. and Oliveros Mata, Eduardo Sergio and Evans, Benjamin A. and Tracy, Joseph B. and Makarov, Denys}, year={2021}, month={Jun} }
 @article{liu_evans_tracy_2020, title={Photothermally Reconfigurable Shape Memory Magnetic Cilia}, volume={5}, ISSN={["2365-709X"]}, url={https://doi.org/10.1002/admt.202000147}, DOI={10.1002/admt.202000147}, abstractNote={AbstractStimulus‐responsive polymers are attractive for microactuators because they can be easily miniaturized and remotely actuated, enabling untethered operation. In this work, magnetic Fe microparticles are dispersed in a thermoplastic polyurethane shape memory polymer matrix and formed into artificial, magnetic cilia by solvent casting within the vertical magnetic field in the gap between two permanent magnets. Interactions of the magnetic moments of the microparticles, aligned by the applied magnetic field, drive self‐assembly of magnetic cilia along the field direction. The resulting magnetic cilia are reconfigurable using light and magnetic fields as remote stimuli. Temporary shapes obtained through combined magnetic actuation and photothermal heating can be locked by switching off the light and magnetic field. Subsequently turning on the light without the magnetic field drives recovery of the permanent shape. The permanent shape can also be reprogrammed after preparing the cilia by applying mechanical constraints and annealing at high temperature. Spatially controlled actuation is demonstrated by applying a mask for optical pattern transfer into the array of magnetic cilia. A theoretical model is developed for predicting the response of shape memory magnetic cilia and elucidates physical mechanisms behind observed phenomena, enabling the design and optimization of ciliary systems for specific applications.}, number={7}, journal={ADVANCED MATERIALS TECHNOLOGIES}, author={Liu, Jessica A. -C. and Evans, Benjamin A. and Tracy, Joseph B.}, year={2020}, month={Jul} }
 @article{roh_okello_golbasi_hankwitz_liu_tracy_velev_2019, title={3D-Printed Silicone Soft Architectures with Programmed Magneto-Capillary Reconfiguration}, volume={4}, ISSN={["2365-709X"]}, DOI={10.1002/admt.201800528}, abstractNote={AbstractSoft intelligent structures that are programmed to reshape and reconfigure under magnetic field can find applications such as in soft robotics and biomedical devices. Here, a new class of smart elastomeric architectures that undergo complex reconfiguration and shape change in applied magnetic fields, while floating on the surface of water, is reported. These magnetoactive soft actuators are fabricated by 3D printing with homocomposite silicone capillary ink. The ultrasoft actuators easily deform by the magnetic force exerted on carbonyl iron particles embedded in the silicone, as well as lateral capillary forces. The tensile and compressive moduli of the actuators are easily determined by their topological design through 3D printing. As a result, their responses can be engineered by the interplay of the intensity of the magnetic field gradient and the programmable moduli. 3D printing allows us to fabricate soft architectures with different actuation modes, such as isotropic/anisotropic contraction and multiple shape changes, as well as functional reconfiguration. Meshes that reconfigure in magnetic fields and respond to external stimuli by reshaping could serve as active tissue scaffolds for cell cultures and soft robots mimicking creatures that live on the surface of water.}, number={4}, journal={ADVANCED MATERIALS TECHNOLOGIES}, publisher={Wiley}, author={Roh, Sangchul and Okello, Lilian B. and Golbasi, Nuran and Hankwitz, Jameson P. and Liu, Jessica A-C and Tracy, Joseph B. and Velev, Orlin D.}, year={2019}, month={Apr} }
 @article{liu_gillen_mishra_evans_tracy_2019, title={Photothermally and magnetically controlled reconfiguration of polymer composites for soft robotics}, volume={5}, ISSN={["2375-2548"]}, url={https://doi.org/10.1126/sciadv.aaw2897}, DOI={10.1126/sciadv.aaw2897}, abstractNote={Combining photothermal heating and magnetic actuation enables the design of untethered, reconfigurable soft robots.}, number={8}, journal={SCIENCE ADVANCES}, author={Liu, Jessica A. -C. and Gillen, Jonathan H. and Mishra, Sumeet R. and Evans, Benjamin A. and Tracy, Joseph B.}, year={2019}, month={Aug} }