Stimuli‐responsive and active materials promise radical advances for many applications. In particular, soft magnetic materials offer precise, fast, and wireless actuation together with versatile ...functionality, while liquid crystal elastomers (LCEs) are capable of large reversible and programmable shape‐morphing with high work densities in response to various environmental stimuli, e.g., temperature, light, and chemical solutions. Integrating the orthogonal stimuli‐responsiveness of these two kinds of active materials could potentially enable new functionalities and future applications. Here, magnetic microparticles (MMPs) are embedded into an LCE film to take the respective advantages of both materials without compromising their independent stimuli‐responsiveness. This composite material enables reconfigurable magnetic soft miniature machines that can self‐adapt to a changing environment. In particular, a miniature soft robot that can autonomously alter its locomotion mode when it moves from air to hot liquid, a vine‐like filament that can sense and twine around a support, and a light‐switchable magnetic spring are demonstrated. The integration of LCEs and MMPs into monolithic structures introduces a new dimension in the design of soft machines and thus greatly enhances their use in applications in complex environments, especially for miniature soft robots, which are self‐adaptable to environmental changes while being remotely controllable.
A liquid crystal elastomer material with embedded ferromagnetic microparticles takes advantage of both magnetic and thermal stimuli‐responsiveness. Such a monolithic soft material enables reconfigurable magnetic soft miniature machines that self‐adapt to changing environmental conditions. The hybrid material introduces a multi‐modal actuation and physical intelligence capability for wireless soft machines.
Small-scale soft-bodied machines that respond to externally applied magnetic field have attracted wide research interest because of their unique capabilities and promising potential in a variety of ...fields, especially for biomedical applications. When the size of such machines approach the sub-millimeter scale, their designs and functionalities are severely constrained by the available fabrication methods, which only work with limited materials, geometries, and magnetization profiles. To free such constraints, here, we propose a bottom-up assembly-based 3D microfabrication approach to create complex 3D miniature wireless magnetic soft machines at the milli- and sub-millimeter scale with arbitrary multimaterial compositions, arbitrary 3D geometries, and arbitrary programmable 3D magnetization profiles at high spatial resolution. This approach helps us concurrently realize diverse characteristics on the machines, including programmable shape morphing, negative Poisson's ratio, complex stiffness distribution, directional joint bending, and remagnetization for shape reconfiguration. It enlarges the design space and enables biomedical device-related functionalities that are previously difficult to achieve, including peristaltic pumping of biological fluids and transport of solid objects, active targeted cargo transport and delivery, liquid biopsy, and reversible surface anchoring in tortuous tubular environments withstanding fluid flows, all at the sub-millimeter scale. This work improves the achievable complexity of 3D magnetic soft machines and boosts their future capabilities for applications in robotics and biomedical engineering.
Miniature untethered robots attract growing interest as they have become more functional and applicable to disruptive biomedical applications recently. Particularly, the soft ones among them exhibit ...unique merits of compliance, versatility, and agility. With scarce onboard space, these devices mostly harvest energy from environment or physical fields, such as magnetic and acoustic fields and patterned lights. In most cases, one device only utilizes one energy transmission mode (ETM) in powering its activities to achieve programmed tasks, such as locomotion and object manipulation. But real‐world tasks demand multifunctional devices that require more energy in various forms. This work reports a liquid metal‐elastomer composite with dual‐ETM using one magnetic field for miniature untethered multifunctional robots. The first ETM uses the low‐frequency (<100 Hz) field component to induce shape‐morphing, while the second ETM employs energy transmitted via radio‐frequency (20 kHz–300 GHz) induction to power onboard electronics and generate excess heat, enabling new capabilities. These new functions do not disturb the shape‐morphing actuated using the first ETM. The reported material enables the integration of electric and thermal functionalities into soft miniature robots, offering a wealth of inspirations for multifunctional miniature robots that leverage developments in electronics to exhibit usefulness beyond self‐locomotion.
This work presents a dual‐energy transfer pipeline (dual‐ETP) soft material by embedding liquid metal into magnetically responsive elastomer. This material integrates dual‐ETP using global magnetic fields and does not complicate the setup. While maintaining all the versatile advantages of conventional magnetically responsive soft materials, this material obtains additional energy in electricity to power onboard electronics and heat for hyperthermia treatment.
Untethered magnetic miniature soft robots capable of accessing hard-to-reach regions can enable safe, disruptive, and minimally invasive medical procedures. However, the soft body limits the ...integration of non-magnetic external stimuli sources on the robot, thereby restricting the functionalities of such robots. One such functionality is localised heat generation, which requires solid metallic materials for increased efficiency. Yet, using these materials compromises the compliance and safety of using soft robots. To overcome these competing requirements, we propose a pangolin-inspired bi-layered soft robot design. We show that the reported design achieves heating > 70 °C at large distances > 5 cm within a short period of time <30 s, allowing users to realise on-demand localised heating in tandem with shape-morphing capabilities. We demonstrate advanced robotic functionalities, such as selective cargo release, in situ demagnetisation, hyperthermia and mitigation of bleeding, on tissue phantoms and ex vivo tissues.
Wireless small-scale soft-bodied devices are capable of precise operation inside confined internal spaces, enabling various minimally invasive medical applications. However, such potential is ...constrained by the small output force and low work capacity of the current miniature soft actuators. To address this challenge, we report a small-scale soft actuator that harnesses the synergetic interactions between the coiled artificial muscle and radio frequency-magnetic heating. This wirelessly controlled actuator exhibits a large output force (~3.1 N) and high work capacity (3.5 J/g). Combining this actuator with different mechanical designs, its tensile and torsional behaviors can be engineered into different functional devices, such as a suture device, a pair of scissors, a driller, and a clamper. In addition, by assuming a spatially varying magnetization profile, a multilinked coiled muscle can have both magnetic field-induced bending and high contractile force. Such an approach could be used in various future untethered miniature medical devices.
The Sengkang General Hospital Orthopaedic Spine Outpatient Service is facing a growing challenge of increasing number of referrals and waiting times, placing a significant burden on the system. ...Primary care referrals have an average wait time of 61.1 days, with 34.5%f patients waiting longer than 60 days from referral to appointment, to see a spine physician.Back pain is a very common presentation, with the vast majority resolving after conservative management which commonly includes analgesia, physiotherapy and reassurance. Unfortunately, many referrals from primary care involve patients who have yet to explore the avenues of conservative management with 90% of our referrals being managed without surgery. Globally, triage services in Western countries conducted by allied health professionals have shown to be an effective method at addressing the escalating wait times with high satisfaction rates. We have endeavoured to emulate this within our department through the implementation of the Spine Triage and Rehabilitation (STAR) Clinic. The STAR clinic aims to empower physiotherapists with the ability to triage patients into surgical and non-surgical categories with their primary physiotherapy expertise to reduce waiting times and increase outpatient capacity.More than 300 patients were recruited, and their progress was tracked over 13 months under the four Ss of: waiting timeS, cost Savings, Safety and patient Satisfaction. This pilot study has been overwhelmingly positive, with significantly reduced waiting times and high cost savings, without any compromise on patient safety and satisfaction.
A key challenge in electronic textiles is to develop an intrinsically conductive thread of sufficient robustness and sensitivity. Here, we demonstrate an elastomeric functionalized microfiber sensor ...suitable for smart textile and wearable electronics. Unlike conventional conductive threads, our microfiber is highly flexible and stretchable up to 120% strain and possesses excellent piezoresistive characteristics. The microfiber is functionalized by enclosing a conductive liquid metallic alloy within the elastomeric microtube. This embodiment allows shape reconfigurability and robustness, while maintaining an excellent electrical conductivity of 3.27 ± 0.08 MS/m. By producing microfibers the size of cotton threads (160 μm in diameter), a plurality of stretchable tubular elastic piezoresistive microfibers may be woven seamlessly into a fabric to determine the force location and directionality. As a proof of concept, the conductive microfibers woven into a fabric glove were used to obtain physiological measurements from the wrist, elbow pit, and less accessible body parts, such as the neck and foot instep. Importantly, the elastomeric layer protects the sensing element from degradation. Experiments showed that our microfibers suffered minimal electrical drift even after repeated stretching and machine washing. These advantages highlight the unique propositions of our wearable electronics for flexible display, electronic textile, soft robotics, and consumer healthcare applications.
Untethered soft miniature robots capable of accessing hard-to-reach regions can enable new, disruptive, and minimally invasive medical procedures. However, once the control input is removed, these ...robots easily move from their target location because of the dynamic motion of body tissues or fluids, thereby restricting their use in many long-term medical applications. To overcome this, we propose a wireless spring-preloaded barbed needle release mechanism, which can provide up to 1.6 N of force to drive a barbed needle into soft tissues to allow robust on-demand anchoring on three-dimensional (3D) surfaces. The mechanism is wirelessly triggered using radio-frequency remote heating and can be easily integrated into existing untethered soft robotic platforms without sacrificing their mobility. Design guidelines aimed at maximizing anchoring over the range of the most biological tissues (kPa range) and extending the operating depth of the device inside the body (up to 75%) are also presented. Enabled by these advances, we achieve robust anchoring on a variety of ex vivo tissues and demonstrate the usage of such a device when integrated with existing soft robotic platforms and medical imaging. Moreover, by simply changing the needle, we demonstrate additional functionalities such as controlled detachment and subsurface drug delivery into 3D cancer spheroids. Given these capabilities, our proposed mechanism could enable the development of a new class of biomedical-related functionalities, such as local drug delivery, disease monitoring, and hyperthermia for future untethered soft medical robots.
Soft-bodied locomotion in fluid-filled confined spaces is critical for future wireless medical robots operating inside vessels, tubes, channels, and cavities of the human body, which are filled with ...stagnant or flowing biological fluids. However, the active soft-bodied locomotion is challenging to achieve when the robot size is comparable with the cross-sectional dimension of these confined spaces. Here, we propose various control and performance enhancement strategies to let the sheet-shaped soft millirobots achieve multimodal locomotion, including rolling, undulatory crawling, undulatory swimming, and helical surface crawling depending on different fluid-filled confined environments. With these locomotion modes, the sheet-shaped soft robot can navigate through straight or bent gaps with varying sizes, tortuous channels, and tubes with a flowing fluid inside. Such soft robot design along with its control and performance enhancement strategies are promising to be applied in future wireless soft medical robots inside various fluid-filled tight regions of the human body.
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