Search

Dexterous magnetic manipulation of ferromagnetic objects is well established, with three to six degrees of freedom possible depending on object geometry1. There are objects for which non-contact dexterous manipulation is desirable that do not contain an appreciable amount of ferromagnetic material but do contain electrically conductive material. Time-varying magnetic fields generate eddy currents in conductive materials2–4, with resulting forces and torques due to the interaction of the eddy currents with the magnetic field. This phenomenon has previously been used to induce drag to reduce the motion of objects as they pass through a static field5–8, or to apply force on an object in a single direction using a dynamic field9–11, but has not been used to perform the type of dexterous manipulation of conductive objects that has been demonstrated with ferromagnetic objects. Here we show that manipulation, with six degrees of freedom, of conductive objects is possible by using multiple rotating magnetic dipole fields. Using dimensional analysis12, combined with multiphysics numerical simulations and experimental verification, we characterize the forces and torques generated on a conductive sphere in a rotating magnetic dipole field. With the resulting model, we perform dexterous manipulation in simulations and physical experiments. Time-varying magnetic fields can be used to manipulate the position and orientation of conductive non-magnetic objects.

Medical procedures often involve a device moving through a natural lumen of the human body (e.g., intestines, blood vessels). However, with existing technology, it is difficult, impossible, or traumatic to reach certain locations. In this article, we present a magnetically actuated soft-robotic concept for use in endoluminal applications (e.g., capsule endoscopes and catheters). The soft endoluminal robot is a simple device comprising two or more permanent magnets, axially magnetized and embedded co-axially with alternating polarity in a compliant body, with an optional internal lumen, actuated by an external rotating magnetic dipole field. We use simulations to elucidate the actuation concept’s underlying physics and, combined with experiments, demonstrate how the proposed concept outperforms other potential variations. We experimentally demonstrate the robustness to misalignment between the soft robot and the applied field, enabling operation in different applications without precise knowledge of the robot’s orientation or precise control of the actuator dipole field. Experiments are then performed inside a synthetic bowel to compare capsule-endoscope-size robots and multi-component robots formed by connecting multiple capsule-endoscope-size robots axially. Finally, experiments in a synthetic stomach show how the concept lends itself to directed self-assembly in the stomach, thus creating robots that are larger than could be swallowed.

In clinical practice, therapeutic and diagnostic endoluminal procedures of the human body often use a scope, catheter, or passive pill-shaped camera. Unfortunately, such devices used in the circulatory system and gastrointestinal tract are often uncomfortable, invasive, and require the patient to be sedated. With current technology, regions of the body are often inaccessible to the clinician. Herein, a magnetically actuated soft endoluminal inchworm robot that may extend clinicians’ ability to reach further into the human body and practice new procedures is described, modeled, and analyzed. A detailed locomotion model is proposed that takes into account the elastic deformation of the robot and its interactions with the environment. The model is validated with in vitro and ex vivo (pig intestine) physical experiments and is shown to capture the robot’s gait characteristics through a lumen. Utilizing dimensional analysis, the effects of the mechanical properties and design variables on the robot’s motion are investigated further to advance the understanding of this endoluminal robot concept.

Dexterous magnetic manipulation of ferromagnetic objects is well established, with three to six degrees of freedom possible depending on object geometry

The use of vertical greenery systems in buildings is becoming more and more common as they provide several benefits, particularly in improving indoor thermal comfort. This paper studies the influence of an indoor living wall on the air temperature and humidity in the test house in Ho Chi Minh City. Effects of the plants, irrigation and ventilation were examined. The temperature and humidity were monitored and analyzed during a 2–month period. The cooling effect of the living wall was proven, with an average reduction of 1°C of the room temperature. Higher air humidity levels were experienced near the green wall, increasing the overall humidity in the room. Irrigation for the plants also helped reduce the room temperature compared to that without irrigation. Therefore, these systems have been proven to be very useful and interesting for warm indoor environments due to the cooling effect.

Acute postoperative pain causes physiological deficits and slows recovery. Reduction of such pain by local anesthetics that are delivered for several days postoperatively is a desirable clinical objective, which is approached by a new formulation and applied in animal studies reported here.We subcutaneously injected a new formulation of poly-lactic-co-glycolic acid polymer microspheres, which provides steady drug release for 96+ hours into rats at the dorsal region 2 hours before surgery. A single 1.2-cm-long skin incision was followed by blunt dissection of skin away from the underlying fascia, and closed by 2 sutures, followed by 14 days of testing. Microspheres containing 5, 10, 20, and 40 mg bupivacaine were injected locally 2 hours before surgery; bupivacaine-free microspheres were the vehicle control, and bupivacaine HCl solution (0.5%), the positive control. Mechanical sensitivity was determined by the frequency of local muscle contractions to repeated pokes with nylon monofilaments (von Frey hairs) exerting 4 and 15 g forces, testing, respectively, allodynia and hyperalgesia, and by pinprick.Injection of bupivacaine microspheres (40 mg drug) into intact skin reduced responses to 15 g von Frey hairs for 6 hours and to pinprick for 36 hours. Respective reductions from bupivacaine HCl lasted for 3 and 2 hours. Skin incision and dissection alone caused mechanical allodynia and hyperalgesia for 14 days. Microspheres containing 20 or 40 mg bupivacaine suppressed postoperative hypersensitivity for up to 3 days, reduced integrated allodynia (area under curve of response versus time) over postoperative days 1 to 5 by 51% ± 20% (mean ± SE) and 78% ± 12%, and reduced integrated hyperalgesia by 55% ± 13% and 64% ± 11%, for the respective doses. Five and ten milligrams bupivacaine in microspheres and the 0.5% bupivacaine solution were ineffective in reducing postoperative hypersensitivity, as were 40 mg bupivacaine microspheres injected contralateral to the incision.Significant suppression of postoperative pain by the slow-release bupivacaine preparation outlasts its anesthetic action on intact skin. These findings demonstrate preventive analgesia and indicate the importance of acute processes in the development of chronic postoperative pain.