CochleRob: Parallel-Serial Robot to Position a Magnetic Actuator around a Patient's Head for Intracochlear Microrobot Navigation.

Our work introduces a new robotic solution named CochleRob, which is used for the administration of super-paramagnetic antiparticles as drug carriers into the human cochlea for the treatment of hearing loss caused by damaged cochlea. This novel robot architecture presents two key contributions. First, CochleRob has been designed to meet specifications pertaining to ear anatomy, including workspace, degrees of freedom, compactness, rigidity, and accuracy. The first objective was to develop a safer mathod to administer drugs to the cochlea without the need for catheter or CI insertion. Secondly, we aimed at developing and validating the mathemathical models, including forward, inverse, and dynamic models, to support the robot function. Our work provides a promising solution for drug administration into the inner ear.

Reprogrammable Ferromagnetic Domains for Reconfigurable Soft Magnetic Actuators.

Soft magnetic materials have shown promise in diverse applications due to their fast response, remote actuation, and large penetration range for various conditions. Herein, a new soft magnetic composite material capable of reprogramming its magnetization profile without changing intrinsic magnetic properties of embedded magnetic particles or the molecular property of base material is reported. This composite contains magnetic microspheres in an elastomeric matrix, and the magnetic microspheres are composed of ferromagnetic microparticles encapsulated with oligomeric-PEG. By controlling the encapsulating polymer phase transition, the magnetization profiles of the magnetic composite can be rewritten by physically realigning the ferromagnetic particles. Diverse magnetic actuators with reprogrammable magnetization profiles are developed to demonstrate the complete reprogramming of complex magnetization profile.

Magnetic Bioreactor for Magneto-, Mechano- and Electroactive Tissue Engineering Strategies.

Biomimetic bioreactor systems are increasingly being developed for tissue engineering applications, due to their ability to recreate the native cell/tissue microenvironment. Regarding bone-related diseases and considering the piezoelectric nature of bone, piezoelectric scaffolds electromechanically stimulated by a bioreactor, providing the stimuli to the cells, allows a biomimetic approach and thus, mimicking the required microenvironment for effective growth and differentiation of bone cells. In this work, a bioreactor has been designed and built allowing to magnetically stimulate magnetoelectric scaffolds and therefore provide mechanical and electrical stimuli to the cells through magnetomechanical or magnetoelectrical effects, depending on the piezoelectric nature of the scaffold. While mechanical bioreactors need direct application of the stimuli on the scaffolds, the herein proposed magnetic bioreactors allow for a remote stimulation without direct contact with the material. Thus, the stimuli application (23 mT at a frequency of 0.3 Hz) to cells seeded on the magnetoelectric, leads to an increase in cell viability of almost 30% with respect to cell culture under static conditions. This could be valuable to mimic what occurs in the human body and for application in immobilized patients. Thus, special emphasis has been placed on the control, design and modeling parameters governing the bioreactor as well as its functional mechanism.

Self-sensing magnetic actuator based on sustainable collagen hybrid nanocomposites.

Taking into account that natural polymers are renewable and biodegradable, hybrid materials based on natural polymers are required for advanced technological applications with reduced environmental footprint. In this work, sustainable composites have been developed based on collagen as a polymeric matrix and different magnetic fillers, in order to tailor magnetic response. The composites were prepared by solution casting with 30 wt% of magnetite nanoparticles (Fe3O4 NPs), magnetite nanorods (Fe3O4 NRs) or cobalt ferrite nanoparticles (CoFe2O4 NPs). It is shown that the magnetic filler type has no bearing on the morphology, physical-chemical, or thermal characteristics of the composites, whereas the mechanical properties are determined by the magnetic filler, leading to a reduction in tensile strength, with values of 4.95 MPa for Fe3O4 NPs, 9.20 MPa for Fe3O4 NRs and 5.21 MPa for CoFe2O4 NPs containing samples. However, the highest magnetization saturation is obtained for Fe3O4 NPs (44 emu.g-1) and the higher coercive field for CoFe2O4 NPs (2062 Oe). In order to prove functionality of the developed composites, a self-sensing magnetic actuator device has been developed with the composite film with CoFe2O4 NPs, showing high stability over cycling.

Reconfigurable Growth of Engineered Living Materials.

The growth of multicellular organisms is a process akin to additive manufacturing where cellular proliferation and mechanical boundary conditions, among other factors, drive morphogenesis. Engineers have limited ability to engineer morphogenesis to manufacture goods or to reconfigure materials comprised of biomass. Herein, a method that uses biological processes to grow and regrow magnetic engineered living materials (mELMs) into desired geometries is reported. These composites contain Saccharomyces cerevisiae and magnetic particles within a hydrogel matrix. The reconfigurable manufacturing process relies on the growth of living cells, magnetic forces, and elastic recovery of the hydrogel. The mELM then adopts a form in an external magnetic field. Yeast within the material proliferates, resulting in 259 ± 14% volume expansion. Yeast proliferation fixes the magnetic deformation, even when the magnetic field is removed. The shape fixity can be up to 99.3 ± 0.3%. The grown mELM can recover up to 73.9 ± 1.9% of the original form by removing yeast cell walls. The directed growth and recovery process can be repeated at least five times. This work enables ELMs to be processed and reprocessed into user-defined geometries without external material deposition.

Alginate Hydrogels Reinforced by Dehydration under Stress-Application to a Soft Magnetic Actuator.

We investigated the effect of partial dehydration under mechanical stress in the properties of alginate hydrogels. For this aim, we characterized the mechanical properties of the hydrogels under tensile and shear stress, as well as their swelling behavior, macroscopic appearance, and microscopic structure. We found that the processes of dehydration under a mechanical stress were irreversible with fully rehydration being impossible. What is more, these processes gave rise to an enhancement of the mechanical robustness of the hydrogels beyond the effect due to the increase in polymer concentration caused by dehydration. Finally, we analyzed the applicability of these results to alginate-based magnetic hydrogel grippers that bended in response to an applied magnetic field. Remarkably, our study demonstrated that the dehydration of the magnetic hydrogels under compression facilitated their bending response.

Magnetically Actuated Hydrogel Stamping-Assisted Cellular Mechanical Analyzer for Stored Blood Quality Detection.

Cellular mechanical property analysis reflecting the physiological and pathological states of cells plays a crucial role in assessing the quality of stored blood. However, its complex equipment needs, operation difficulty, and clogging issues hinder automated and rapid biomechanical testing. Here, we propose a promising biosensor assisted by magnetically actuated hydrogel stamping to fulfill it. The flexible magnetic actuator triggers the collective deformation of multiple cells in the light-cured hydrogel, and it allows for on-demand bioforce stimulation with the advantages of portability, cost-effectiveness, and simplicity of operation. The magnetically manipulated cell deformation processes are captured by the integrated miniaturized optical imaging system, and the cellular mechanical property parameters are extracted from the captured images for real-time analysis and intelligent sensing. In this work, 30 clinical blood samples with different storage durations (<14 days and >14 days) were tested. A deviation of 3.3% in the differentiation of blood storage durations by this system compared to physician annotation demonstrated its feasibility. This system should broaden the application of cellular mechanical assays in diverse clinical settings.

Magneto-Responsive Actuating Surfaces with Controlled Wettability and Optical Transmittance.

The wettability of surfaces can be manipulated using actuating micro/nanostructures, as in the manipulation of water droplets with magnetic forces. Controlling water droplets with magneto-responsive surfaces is limited to optical applications, however, because these surfaces are normally opaque. Herein, we introduce a magneto-responsive actuating surface that is capable of controlling not only the wettability but also the optical transmittance. The magneto-responsive actuating surface is fabricated using a composite of iron particles with polydimethylsiloxane (PDMS). Thanks to the elastic properties of PDMS, fabricated microstructures' bending is induced by applying magnetic force. Therefore, the static/dynamic water contact angle and the optical transmittance can be controlled. Furthermore, as a feasible application, a sliding angle control system that depends on the magnet location is implemented. On the basis of the interesting characteristics of not only wettability but also optical transmittance, this study is expected to be widely used in various fields such as optics, surface self-cleaning systems of solar cells, and smart windows.

Design and Fabrication of a Magnetic Actuator for Torque and Force Control Estimated by the ANN/SA Algorithm.

Magnetic manipulation has the potential to recast the medical field both from an operational and drug delivery point of view as it can provide wireless controlled navigation over surgical devices and drug containers inside a human body. The presented system in this research implements a unique eight-coil configuration, where each coil is designed based on the characterization of the working space, generated force on a milliscale robot, and Fabry factor. A cylindrical iron-core coil with inner and outer diameters and length of 20.5, 66, and 124 mm is the optimized coil. Traditionally, FEM results are adopted from simulation and implemented into the motion logic; however, simulated values are associated with errors; 17% in this study. Instead of regularizing FEM results, for the first time, artificial intelligence has been used to approximate the actual values for manipulation purposes. Regression models for Artificial Neural Network (ANN) and a hybrid method called Artificial Neural Network with Simulated Annealing (ANN/SA) have been created. ANN/SA has shown outstanding performance with an average R2, and a root mean square error of 0.9871 and 0.0153, respectively. Implementation of the regression model into the manipulation logic has provided a motion with 13 µm of accuracy.

Lorentz Force Actuated Tunable-Focus Liquid Lens.

Tunable-focus liquid lenses provide focal length tuning for optical systems, e.g., cameras, where physical movement of rigid lenses are not an option or not preferable. In this work we present a magnetically actuated liquid lens utilizing the Lorentz force to vary the focal length as the current through the system is varied. The resulting lens can operate as both a diverging and a converging lens depending on the direction of current applied and has a large range of focal lengths, from -305 mm to -111 mm and from 272 mm to 146 mm. We also characterized the aberrations of the lens during the actuation with a Shack-Hartmann wavefront sensor, and utilized the lens for imaging, during which we measured a resolution of 7.13 lp/mm.

The Design, Fabrication, and Testing of an Electromagnetic Micropump with a Matrix-Patterned Magnetic Polymer Composite Actuator Membrane.

A valveless electromagnetic (EM) micropump with a matrix-patterned magnetic polymer composite actuator membrane structure was successfully designed and fabricated. The composite membrane structure is made of polydemethylsiloxane (PDMS) that is mixed with magnetic particles and patterned in matrix blocks. The matrix magnetic composite membrane was fabricated using a soft lithography process and expected to have a compact structure having sufficient magnetic force for membrane deformation and maintained membrane flexibility. The magnetic membrane was integrated with the microfluidic system and functionally tested. The experimental results show that a magnetic composite actuator membrane containing of 6% NdFeB is capable of producing a maximum membrane deflection up to 12.87 µm. The functionality test of the EM actuator for fluid pumping resulted in an extremely low sample injection flow rate of approximately 6.523 nL/min. It was also concluded that there is a correlation between the matrix structure of the actuator membrane and the fluid pumping flow rate. The injection flow rate of the EM micropump can be controlled by adjusting the input power supplied to the EM coil, and this is believed to improve the injection accuracy of the drug dosage and have potential in improving the proficiency of the existing drug delivery system.