Measurements of Electrodermal Activity, Tissue Oxygen Saturation, and Visual Analog Scale for Different Cuff Pressures.

The quantification of comfort in binding parts, essential human-machine interfaces (HMI) for the functioning of rehabilitation robots, is necessary to reduce physical strain on the user despite great achievements in their structure and control. This study aims to investigate the physiological impacts of binding parts by measuring electrodermal activity (EDA) and tissue oxygen saturation (StO2). In Experiment 1, EDA was measured from 13 healthy subjects under three different pressure conditions (10, 20, and 30 kPa) for 1 min using a pneumatic cuff on the right thigh. In Experiment 2, EDA and StO2 were measured from 10 healthy subjects for 5 min. To analyze the correlation between EDA parameters and the decrease in StO2, a survey using the visual analog scale (VAS) was conducted to assess the level of discomfort at each pressure. The EDA signal was decomposed into phasic and tonic components, and the EDA parameters were extracted from these two components. RM ANOVA and a post hoc paired t-test were used to determine significant differences in parameters as the pressure increased. The results showed that EDA parameters and the decrease in StO2 significantly increased with the pressure increase. Among the extracted parameters, the decrease in StO2 and the mean SCL proved to be effective indicators. Such analysis outcomes would be highly beneficial for studies focusing on the comfort assessment of the binding parts of rehabilitation robots.

Photoinitiated Polymerization of Hydrogels by Graphene Quantum Dots.

As a smart stimulus-responsive material, hydrogel has been investigated extensively in many research fields. However, its mechanical brittleness and low strength have mattered, and conventional photoinitiators used during the polymerization steps exhibit high toxicity, which limits the use of hydrogels in the field of biomedical applications. Here, we address the dual functions of graphene quantum dots (GQDs), one to trigger the synthesis of hydrogel as photoinitiators and the other to improve the mechanical strength of the as-synthesized hydrogel. GQDs embedded in the network effectively generated radicals when exposed to sunlight, leading to the initiation of polymerization, and also played a significant role in improving the mechanical strength of the crosslinked chains. Thus, we expect that the resulting hydrogel incorporated with GQDs would enable a wide range of applications that require biocompatibility as well as higher mechanical strength, including novel hydrogel contact lenses and bioscaffolds for tissue engineering.

4D-bioprinted silk hydrogels for tissue engineering.

Recently, four-dimensional (4D) printing is emerging as the next-generation biofabrication technology. However, current 4D bioprinting lacks biocompatibility or multi-component printability. In addition, suitable implantable targets capable of applying 4D bioprinted products have not yet been established, except theoretical and in vitro study. Herein, we describe a cell-friendly and biocompatible 4D bioprinting system including more than two cell types based on digital light processing (DLP) and photocurable silk fibroin (Sil-MA) hydrogel. The shape changes of 3D printed bilayered Sil-MA hydrogels were controlled by modulating their interior or exterior properties in physiological conditions. We used finite element analysis (FEA) simulations to explore the possible changes in the complex structure. Finally, we made trachea mimetic tissue with two cell types using this 4D bioprinting system and implanted it into a damaged trachea of rabbit for 8 weeks. The implants were integrated with the host trachea naturally, and both epithelium and cartilage were formed at the predicted sites. These findings demonstrate that 4D bioprinting system could make tissue mimetic scaffold biologically and suggest the potential value of the 4D bioprinting system for tissue engineering and the clinical application.

Human-mimetic soft robot joint for shock absorption through joint dislocation.

This paper presents a human-mimetic manipulator capable of shock absorption by using dislocation at the soft joint. A one degree-of-freedom (DOF) soft robot joint was developed based on the human elbow-joint structure, especially mimicking the humeroulnar joint in the elbow. Each component of the soft joint is combined by an elastic ligament, which is made up of elastic rubber and is attached to the pivot joint pin positioned at a predetermined place according to a specially designed pin guide. As an external impact is applied to the joint, the elastic ligament is elongated as the pivot joint pin is moved from the predetermined place. This state is defined as a dislocation, which is similar to the dislocation of a human joint when impacted. Dislocation in the proposed soft robot joint occurred when the external impact was larger than the predetermined threshold force. This threshold force can be predicted by the modulus of the elastic ligament and the shape of the pin guide, and the theoretical model was developed in this study. To evaluate the function of dislocation, dynamic and quasi-static impact tests were performed at the 1-DOF soft robot joint. Moreover, the human-mimetic manipulator is proposed based on the 2-DOF soft robot joint. This manipulator can realize four motions of a human arm using the pneumatic artificial muscles: flexion, extension, pronation and supination. Each artificial muscle and bone structure were similar to the human arm structure, and thus the configuration of each bone structure of the manipulator for each motion is similar to the configurations of a human skeletal structure. This manipulator was also capable of dislocation to absorb the external impact. The developed human-mimetic manipulator with a soft joint is expected to be applied to a naturally safe humanoid robot that works with humans in the same space.

Turtle mimetic soft robot with two swimming gaits.

This paper presents a biomimetic turtle flipper actuator consisting of a shape memory alloy composite structure for implementation in a turtle-inspired autonomous underwater vehicle. Based on the analysis of the Chelonia mydas, the flipper actuator was divided into three segments containing a scaffold structure fabricated using a 3D printer. According to the filament stacking sequence of the scaffold structure in the actuator, different actuating motions can be realized and three different types of scaffold structures were proposed to replicate the motion of the different segments of the flipper of the Chelonia mydas. This flipper actuator can mimic the continuous deformation of the forelimb of Chelonia mydas which could not be realized in previous motor based robot. This actuator can also produce two distinct motions that correspond to the two different swimming gaits of the Chelonia mydas, which are the routine and vigorous swimming gaits, by changing the applied current sequence of the SMA wires embedded in the flipper actuator. The generated thrust and the swimming efficiency in each swimming gait of the flipper actuator were measured and the results show that the vigorous gait has a higher thrust but a relatively lower swimming efficiency than the routine gait. The flipper actuator was implemented in a biomimetic turtle robot, and its average swimming speed in the routine and vigorous gaits were measured with the vigorous gait being capable of reaching a maximum speed of 11.5 mm s(-1).

The Effect and Safety of Steroid Injection in Lumbar Spinal Stenosis: With or Without Local Anesthetics.

OBJECTIVE: To compare the long-term effect and safety of an epidural steroid injection in spinal stenosis patients, with or without local anesthetics. METHODS: Twenty-nine patients diagnosed with spinal stenosis were included and randomly divided into two groups. Translaminar epidural and selective nerve root spinal injection procedures were performed using steroids mixed with local anesthetics or normal saline. The effects of spinal injection procedures were measured with visual analogue scale (VAS) and functional rate index (FRI). These measurements were performed before injection, at 1 month after injection and at 3 months after injection. The occurrence of side effects was investigated each time. RESULTS: The VAS and FRI scores were significantly reduced in both the local anesthetics group and normal saline group at 1 and 3 months after the injection. However, there was no significant difference in VAS and FRI score reduction between the two groups each time. Side effects are not noted in both groups. CONCLUSION: The spinal injection procedures using steroids mixed either with local anesthetics or normal saline have an effect in reducing pain and improving functional activities. However, there was no significant difference between the two groups in relation to side effects and the long-term effects of pain and function.

35 Hz shape memory alloy actuator with bending-twisting mode.

Shape Memory Alloy (SMA) materials are widely used as an actuating source for bending actuators due to their high power density. However, due to the slow actuation speed of SMAs, there are limitations in their range of possible applications. This paper proposes a smart soft composite (SSC) actuator capable of fast bending actuation with large deformations. To increase the actuation speed of SMA actuator, multiple thin SMA wires are used to increase the heat dissipation for faster cooling. The actuation characteristics of the actuator at different frequencies are measured with different actuator lengths and results show that resonance can be used to realize large deformations up to 35 Hz. The actuation characteristics of the actuator can be modified by changing the design of the layered reinforcement structure embedded in the actuator, thus the natural frequency and length of an actuator can be optimized for a specific actuation speed. A model is used to compare with the experimental results of actuators with different layered reinforcement structure designs. Also, a bend-twist coupled motion using an anisotropic layered reinforcement structure at a speed of 10 Hz is also realized. By increasing their range of actuation characteristics, the proposed actuator extends the range of application of SMA bending actuators.

Monolimb paralysis after laparoscopic appendectomy due to conversion disorder.

Limb paralysis can develop for various reasons. We found a 13-year-old patient who became paralyzed in her lower extremities after laparoscopic appendectomy. Some tests, including electrodiagnostic studies and magnetic resonance imaging, were performed to evaluate the cause of lower limb paralysis. None of the tests yielded definite abnormal findings. We subsequently decided to explore the possibility of psychological problems. The patient was treated with simultaneous rehabilitation and psychological counseling. Paralysis of the patient's lower extremity improved gradually and the patient returned to normal life. Our findings indicate that psychological problems can be related to limb paralysis without organ damage in patients who have undergone laparoscopic surgical procedures.

Locomotion of inchworm-inspired robot made of smart soft composite (SSC).

A soft-bodied robot made of smart soft composite with inchworm-inspired locomotion capable of both two-way linear and turning movement has been proposed, developed, and tested. The robot was divided into three functional parts based on the different functions of the inchworm: the body, the back foot, and the front foot. Shape memory alloy wires were embedded longitudinally in a soft polymer to imitate the longitudinal muscle fibers that control the abdominal contractions of the inchworm during locomotion. Each foot of the robot has three segments with different friction coefficients to implement the anchor and sliding movement. Then, utilizing actuation patterns between the body and feet based on the looping gait, the robot achieves a biomimetic inchworm gait. Experiments were conducted to evaluate the robot's locomotive performance for both linear locomotion and turning movement. Results show that the proposed robot's stride length was nearly one third of its body length, with a maximum linear speed of 3.6 mm s(-1), a linear locomotion efficiency of 96.4%, a maximum turning capability of 4.3 degrees per stride, and a turning locomotion efficiency of 39.7%.