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Stomach cancer is a global health concern as millions of cases are reported each year. In the present study, we developed a pH-responsive microrobot with good biocompatibility, magnetic-field controlled movements, and the ability to be visualized

Four-dimensional (4D) printing is a promising technique that can produce shape-morphing materials to designated stimuli. However, as bilayered structures with varying mechanical properties are requ...

Microrobots that can be precisely guided to target lesions have been studied for in vivo medical applications. However, existing microrobots have challenges in vivo such as biocompatibility, biodegradability, actuation module, and intra- and postoperative imaging. This study reports microrobots visualized with real-time x-ray and magnetic resonance imaging (MRI) that can be magnetically guided to tumor feeding vessels for transcatheter liver chemoembolization in vivo. The microrobots, composed of a hydrogel-enveloped porous structure and magnetic nanoparticles, enable targeted delivery of therapeutic and imaging agents via magnetic guidance from the actuation module under real-time x-ray imaging. In addition, the microrobots can be tracked using MRI as postoperative imaging and then slowly degrade over time. The in vivo validation of microrobot system–mediated chemoembolization was demonstrated in a rat liver with a tumor model. The proposed microrobot provides an advanced medical robotic platform that can overcome the limitations of existing microrobots and current liver chemoembolization.

Several recent advances have emerged in biotherapy and the development of personal drugs. However, studies exploring effective manufacturing methods of personal drugs remain limited. In this study, solid drugs based on poly(ethylene glycol)diacrylate (PEGDA) hydrogel and doxorubicin were fabricated, and their final geometry was varied through UV-light patterning. The results suggested that the final drug concentration was affected by the geometrical volume as well as the UV-light exposure time. The analysis of PEGDA showed no effect on the surrounding cells, indicating its high biocompatibility. However, with the addition of doxorubicin, it showed an excellent therapeutic effect, indicating that drugs inside the PEGDA structure could be successfully released. This approach enables personal drugs to be fabricated in a simple, fast, and uniform manner, with perfectly tuned geometry.

The ability to manipulate therapeutic agents in fluids is of interest to improve the efficiency of targeted drug delivery. Ultrasonic manipulation has great potential in the field of therapeutic applications as it can trap and manipulate micro-scale objects. Recently, several methods of ultrasonic manipulation have been studied through standing wave, traveling wave, and acoustic streaming. Among them, the traveling wave based ultrasonic manipulation is showing more advantage for in vivo environments. In this paper, we present a novel ultrasonic transducer (UT) array with a hemispherical arrangement that generates active traveling waves with phase modulation to manipulate a micromotor in water. The feasibility of the method could be demonstrated by in vitro and ex vivo experiments conducted using a UT array with 16 transducers operating at 1 MHz. The phase of each transducer was controlled independently for generating a twin trap and manipulation of a micromotor in 3D space. This study shows that the ultrasonic manipulation device using active traveling waves is a versatile tool that can be used for precise manipulation of a micromotor inserted in a human body and targeted for drug delivery.

Targeted drug delivery using a microrobot is a promising technique capable of overcoming the limitations of conventional chemotherapy that relies on body circulation. However, most studies of microrobots used for drug delivery have only demonstrated simple mobility rather than precise targeting methods and prove the possibility of biodegradation of implanted microrobots after drug delivery. In this study, magnetically guided self-rolled microrobot that enables autonomous navigation-based targeted drug delivery, real-time X-ray imaging, and microrobot retrieval is proposed. The microrobot, composed of a self-rolled body that is printed using focused light and a surface with magnetic nanoparticles attached, demonstrates the loading of doxorubicin and an X-ray contrast agent for cancer therapy and X-ray imaging. The microrobot is precisely mobilized to the lesion site through automated targeting using magnetic field control of an electromagnetic actuation system under real-time X-ray imaging. The photothermal effect using near-infrared light reveals rapid drug release of the microrobot located at the lesion site. After drug delivery, the microrobot is recovered without potential toxicity by implantation or degradation using a magnetic-field-switchable coiled catheter. This microrobotic approach using automated control method of the therapeutic agents-loaded microrobot has potential use in precise localized drug delivery systems.

The concept of an active drug delivery and controlled drug release using microrobot system has attracted attention over the past decade. However, developing these microrobot system is hindered by the low drug release rate upon external stimuli, such as an alternating magnetic field or light, with a long stimulation period (>40% release upon 10 min stimulation). This study evaluated using self-rolled helical microrobots to provide a controlled drug delivery system that uses magnetic manipulation and provides for highly efficient drug release. The rapid and simple fabrication of helical microrobots that change shape upon exposure to protic/aprotic stimuli was demonstrated using a single-layer self-folding technique. The self-folded helical microrobots navigated in the desired direction using a rotating magnetic field produced by an electromagnetic actuator. After arrival at the target location, non-covalently bonded anti-cancer drugs were released during a short period of ultrasound stimulation. The results demonstrate that, with 1 min of ultrasound stimulation, more than 90% of drug release was achieved. This efficient drug release system could enable the practical application of a microrobot-based drug delivery system.

There are challenges in developing practically viable biopolymer-based actuators with ecofriendly, biocompatible, and biodegradable functionalities. Therefore, we propose a cellulose acetate (CA)-based ecofriendly soft-ionic networking actuator consisting of multifunctional additive polyvinylidene difluoride (PVDF), highly conductive ammonia-functionalized graphene nanoplatelets (AFGNPs), ionic liquids (IL), and flexible conducting polymer poly(3,4-ethylenedioxuthiopene)-polystyrene sulfonate (PEDOT:PSS) as an electrode. The proposed actuator exhibits a large bending displacement and short response time in an open-air environment, resulting from its enhanced electro-chemo-mechanical properties and strong ionic and interfacial interactions. In comparison with CA/PVDF-IL actuator, the CA/PVDF–IL–AFGNPs actuator demonstrates a considerably increased IL uptake and ion-exchange capacity of up to 71.04% and 300.6%, respectively, and an increase in the specific capacitance by over 3.64 times, which lead to bending actuation performances 2.21 and 1.87 times greater, respectively, under AC (4 V) and DC (4 V). Moreover, we demonstrate that a CA/PVDF–IL–AFGNPs actuator with a hierarchical structure shows values that are 1.32, 1.5, and 1.74 times larger than those of a planar actuator in DC (4 V), AC (3 V), and blocking force (4 V), respectively. The developed high-performance CA/PVDF–AFGNPs and the hierarchical surface texture of the patterned CA/PVDF–IL–AFGNPs actuators present these extraordinary achievements together with environmentally friendly materials, a low driving voltage, easy manufacturing, and high actuation performances. Therefore, they can be candidates for human-friendly products (e.g., biomedical devices, bioinspired robots, and soft haptic devices).

Bioinspired soft actuators have received burgeoning interest because of their applications in future electronic devices including soft robots, soft haptic devices, human-friendly flexible wearable devices, and biomedical robots. Here, a biofriendly soft actuator was newly designed based on core-shell-structured bacterial cellulose membrane, which was fabricated by homogeneously depositing polypyrrole nanoparticles on the surface of TEMPO-Oxidized bacterial cellulose (TOBC) nanofibers via a chemical polymerization method. The proposed soft actuator under both harmonic and step electrical inputs showed relatively large bending mechanical deformation, fast response time, and good long-term durability in air condition, which was due to the enhanced electrochemical properties of TOBC-Polypyrrole membrane, resulting from its highly porous structure and high conductivity. Therefore, the designed TOBC-Polypyrrole actuator can be a strong candidate for bioinspired actuating devices such as, soft and wearable electronics, and active biomedical devices.

Ionic-type artificial muscles with eco-friendly, biodegradable, and biocompatible functionalities have attracted attention for a wide range of potential applications in wearable electronics, soft haptic-feedback systems, and active biomedical devices. Here, we report on the development of an ecofriendly high-performance ionic soft actuator based on biofriendly cellulose acetate (CA), graphene nanopowders (GN), ionic liquid (IL) as a plasticizer, and biofriendly-flexible-nonmetallic conducting polymer poly(3,4-ethylene-dioxythiopene)-polystyrenesulfonate (PEDOT: PSS) as an electrode, thereby realizing a novel ecofriendly CA-IL-GN actuator with a large bending mechanical deformation and a fast response time. The proposed CA-IL-GN (0.2 wt%) nanocomposite membrane exhibited dramatic increments in specific capacitance (2.92 times) and Young’s modulus (2.38 times), thus leading to a 2.9 times larger bending deformation and a 4.8 times faster response than those of pure CA-IL actuator. Therefore, the developed ecofriendly high-performance CA-IL-GN actuator can be considered to be a promising candidate for human-friendly electronics, including artificial muscles, flexible haptic devices, soft wearable devices, and bio-medical devices, due to its cost-effectiveness, large bending mechanical actuation, fast response, and bio-friendly functionalities.