Bent Fingers Research Articles

Piezoelectric Properties of As-Spun Poly(vinylidene Fluoride)/Multi-Walled Carbon Nanotube/Zinc Oxide Nanoparticle (PVDF/MWCNT/ZnO) Nanofibrous Films.

Conductive multi-walled carbon nanotubes (MWCNTs) as well as piezoelectric zinc oxide (ZnO) nanoparticles are frequently used as a single additive and dispersed in polyvinylidene fluoride (PVDF) solutions for the fabrication of piezoelectric composite films. In this study, MWCNT/ZnO binary dispersions are used as spinning liquids to fabricate composite nanofibrous films by electrospinning. Binary additives are conducive to increasing the crystallinity, piezoelectric voltage coefficient, and consequent piezoelectricity of as-spun films owing to the stretch-enhanced polarization of the electrospinning process under an applied electric field. PCZ-1.5 film (10 wt. % PVDF/0.1 wt. % MWCNTs/1.5 wt. % ZnO nanoparticles) contains the maximum β-phase content of 79.0% and the highest crystallinity of 87.9% in nanofibers. A sensor using a PCZ-1.5 film as a functional layer generates an open-circuit voltage of 10 V as it is subjected to impact loads with an amplitude of 6 mm at 10 Hz. The piezoelectric sensor reaches a power density of 0.33 μW/cm2 and a force sensitivity of 582 mV/N. In addition, the sensor is successfully applied to test irregular motions of a bending finger and stepping foot. The result indicates that electrospun PVDF/MWCNT/ZnO nanofibrous films are suitable for wearable devices.

Formation Mechanism of Fingers That Protrude Eastward From the Io Plasma Disk During the Interchange Instability

AbstractThe solar wind‐magnetosphere‐ionosphere interaction at Jupiter is reproduced numerically adopting the nine‐component magnetohydrodynamic simulation. Calculations take into account the magnetosphere‐ionosphere coupling, Jovian rotation, and Io plasma source. High‐speed rotating plasma inside restricted magnetospheric space causes expansion and contraction of magnetic field, forming super‐rotation at radial distance 20∼30 Rj and co‐rotation breakdown further outside. Field‐perpendicular current that restores co‐rotational delay beyond 30 Rj is connected via field‐aligned current to the main oval in the ionosphere. Inside 20 Rj, there is almost co‐rotation region (deviation from co‐rotation less than 20 km/s). Particularly within 10 Rj, the deviation from co‐rotation is less than 2 km/s. In the nearly co‐rotating region, the Io plasma forms a disk structure through field‐aligned redistribution. The interchange instability occurs near the outer wall of the Io plasma disk, and instability flow develops to vortex. Through this instability, a part of the centrifugal drift current supporting the Io plasma disk is connected to low‐latitude field‐aligned current that generates beads‐like spots on the lower latitude side of the main oval. Resulting interchange instability comes to satisfy the structure of convection and enables further development of vortex. The Coriolis force acting on eastward flow inside the developing vortex makes this flow protrude further outward, forming eastward bending fingers. Inside 10 Rj, Io plasma transport by the interchange instability becomes slower, despite the center of the disk. Io plasma escapes from the inner magnetosphere with a time constant of 20 days if this slow transport is taken into account.

Mutations in LIFR rewire the JAK/STAT signaling pathway: A study unveiling mechanistic details of Stüve-Wiedemann syndrome

Stüve-Wiedemann syndrome (SWS), a rare autosomal recessive disorder, characterized by diminutive size, curvature of the elongated bones, bent fingers, episodes of heightened body temperature, respiratory distress or periods of breath-holding, and challenges with feeding, especially causes fatality in infants. SWS is an outcome of potential missense mutations in the leukemia inhibitory factor receptor gene reflected as numerous amino acid mutations at protein level. Employing in silico tools and techniques like mutational screening with Pred_MutHTP, I-Mutant2.0, PANTHER.db, PolyPhen, to classify mutations as deleterious/destabilizing, in conjunction with experimental data analysis, P136A and S279P emerged as ‘effect’-causing mutations. Pre-existing knowledge suggests, SWS progression is effectuated conformationally altered and dysfunctional LIFR, unable to bind to LIF and further form the LIF/LIFR/gp130 signalling complex. To gain functional insights into the effect of the said mutations on the wild type protein, an all-atom, explicit, solvent molecular dynamics simulation was performed following docking approaches. Consequently, referring to the RMSD, RMSF, protein dynamic network analysis, energy landscape plots and domain motion analysis, it was revealed that unbound LIFR_WT was more prone to LIF binding as usual whereas the mutants exhibited considerable domain closure to inhibit LIF binding. We conducted binding affinity analysis via MM/GBSA and dissociation constant estimation after LIFR-LIF docking and found the WT_complex to be more stable and compact as a whole when compared to the flexible mutant complexes thus being associated with SWS. Our study offers a route for understanding molecular level implications upon LIFR mutations which opens an avenue for therapeutic interventions.

Smart Control of Home Appliances Using Hand Gesture Recognition in an IoT-Enabled System

ABSTRACT Recently, with the vigorous development of the Internet of Things (IoT) technology, all kinds of intelligent home appliances in the market are constantly innovating. The public requirements for residential safety and convenience are also increasing. Meanwhile, with the improvement of indigenous medical technology and quality of life, people’s average lifespan is gradually increasing. However, countries around the world are facing the problem of aging societies. Hand gesture recognition is gaining popularity in the fields of gesture control, robotics, or medical applications. Therefore, how to create a convenient and smart control system of home appliances for the elderly or the disabled has become the objective of this study. It aims to use Google MediaPipe to develop a hand tracking system, which detected 21 key points of a hand through the camera lens of a mobile device and used a vector formula to calculate the angle of the intersection of two lines based on four key points. After the angle of bending finger is obtained, users’ hand gesture can be recognized. Our experiments have confirmed that the recognition precision and recall values of hand gesture for numbers 0–9 reached 98.80% and 97.67%, respectively; and the recognition results were used to control home appliances through the low-cost IoT-Enabled system.

Stretchable self-adhesive and self-powered smart bandage for motion perception and motion intention recognition

The research on flexible and stretchable self-powered sensors perceiving human body motion and physiological signals has become a hot spot in recent years. Aided with machine learning, more features of the human motion and physiological signals can be intelligently interpreted. Here, we first propose a triboelectric nanogenerator (BMS-TENG) based on highly conductive multi-walled carbon nanotubes, flexible and stretchable silica gel, and a self-adhesive elastic bandage, which is highly stretchable and self-adhesive for easy fixation on the skin. The maximum stretchability of the sensor is 502%. BMS-TENG sensor can collect a variety of human motion and physiological signals, such as bending fingers and elbows, lifting legs, breathing, and swallowing. With the support of machine learning, we propose a smart bandage system capable of acquiring motion signals and recognizing intentions. By collecting signals from the forearm near the elbow instead of the fingers, the smart bandage can recognize various gestures and muscle action features. Applications of intention-manipulating diverse gestures from the robotic hand and individual identification work well. The system has great potential in human motion monitoring, electronic skin, human-computer interaction, gesture recognition, biomedicine, and other fields.

Curvature Tracking of a Two-Segmented Soft Finger Using an Adaptive Sliding-Mode Controller

The emergence of soft robotics in the last decade has brought about the exponential usage of elastomer bending robots in numerous fields of expertise from prosthetic hands to industrial grippers. While considerable attention has been drawn to static grasp, a substantial gap can be recognized in the development of soft grippers and anthropomorphic hands with the ability to manipulate objects dynamically, an ability that is referred to as in-hand object manipulation. In order to fill this gap, efficient and practical approaches should be investigated for the fabrication, modeling, and control of soft robots that are computationally efficient and capable of yielding repeatable results. Accordingly, in this article, qualified approaches for the dynamic modeling and control of a soft bending finger are introduced that can be efficiently implemented for planar in-hand manipulation applications in soft robotics. In this regard, a novel 3-D-printed mold is designed to cast a uniformly fabricated soft finger consisting of two independently actuated bending segments. After deriving the dynamic model of the soft finger and identifying its dynamic parameters, an adaptive sliding-mode controller is proposed to guarantee the convergence of the bending angles to desired trajectories under dynamic uncertainties and external disturbances. In the experimental validations, the root-mean-square errors of the proposed controller are 0.0323 and 0.0303 rad/m in free motion for each segment, while these numbers are 0.0328 and 0.0226 rad/m for constrained motion. For a comparative evaluation of the proposed controller, the results of the proportional–integral–differential controller are demonstrated under similar circumstances.

3D Surface Topographic Optical Scans Yield Highly Reliable Global Spine Range of Motion Measurements in Scoliotic and Non-Scoliotic Adolescents.

Adolescent idiopathic scoliosis results in three dimensional changes to a patient's body, which may change a patient's range of motion. Surface topography is an emerging technology to evaluate three dimensional parameters in patients with scoliosis. The goal of this paper is to introduce novel and reliable surface topographic measurements for the assessment of global coronal and sagittal range of motion of the spine in adolescents, and to determine if these measurements can distinguish between adolescents with lumbar scoliosis and those without scoliosis. This study is a retrospective cohort study of a prospectively collected registry. Using a surface topographic scanner, a finger to floor and lateral bending scans were performed on each subject. Inter- and intra-rater reliabilities were assessed for each measurement. ANOVA analysis was used to test comparative hypotheses. Inter-rater reliability for lateral bending fingertip asymmetry (LBFA) and lateral bending acromia asymmetry (LBAA) displayed poor reliability, while the coronal angle asymmetry (CAA), coronal angle range of motion (CAR), forward bending finger to floor (FBFF), forward bending acromia to floor (FBAF), sagittal angle (SA), and sagittal angle normalized (SAN) demonstrated good to excellent reliability. There was a significant difference between controls and lumbar scoliosis patients for LBFA, LBAA, CAA and FBAF (p-values < 0.01). Surface topography yields a reliable and rapid process for measuring global spine range of motion in the coronal and sagittal planes. Using these tools, there was a significant difference in measurements between patients with lumbar scoliosis and controls. In the future, we hope to be able to assess and predict perioperative spinal mobility changes.

Transparent self-powered triboelectric sensor based on PVA/PA hydrogel for promoting human-machine interaction in nursing and patient safety

Human-machine interaction (HMI) has made great progress in the intelligent medical system, realizing the interaction between patients, medical staff and medical equipment. Here, we report a triboelectric nanogenerator with the flexible-stretchable polyvinyl alcohol/phytic acid (PVA/PA) hydrogel for self-powered HMI sensing in intelligent medical system. Benefiting from effective optimization design of materials, it possesses excellent mechanical and electrical properties, such as over 20,000 cycles durability, transparency, flexibility, and power density up to 1.33 W·m−2. The device has a linearity of up to 0.949 in the tensile range of 200% and 0.992 in the bending angle range from 30° to 90°, respectively. Through processing and encoding the electrical signals collected by multiple channels in independent or synergistic mode, a self-powered medical nursing HMI system attached to patient fingers was developed to provide real-time help and assistance for both patients and medical staff, which the demand for distress calls can be successfully transmitted with just gently bending fingers in diagnosis. This work exhibits the application value of the self-powered triboelectric sensor to the medical HMI field, and can be extended to other aspects, showing a broad impact in brain computer interface.

Development of Topology Optimized Bending-Twisting Soft Finger

Abstract This paper proposed a systematic framework to automatically design and fabricate optimized soft robotic fingers. The soft finger is composed of a soft silicone structure with inner air chambers and a harder outer layer, which are fabricated by molding process and 3D printing, respectively. The softer layer is utilized for actuation while the supportive hard structure is used to impose constraints. The framework applies a topology optimization approach based on rational approximation of material properties (RAMP) method to obtain an optimal design of the outer layer of the soft fingers. Two basic motion primitives (bending and twisting) of the soft finger were explored. A multi-segmented soft bending finger and a soft twisting finger were designed and fabricated through the proposed framework. This work also explored the combination of bending and twisting primitives by developing a combined bending-twisting soft finger. The soft fingers were characterized by free and blocked movement tests. The experiments showed that the triple-segmented soft finger can achieve a maximum of 50.5 deg no-load bending under the actuation pressure of 53 kPa. The blocked movement test on the multi-segmented soft actuating finger showed that this finger could generate up to a maximum of 0.63 N force under 57 kPa actuation pressure in 7 s of inflating time. The developed twisting soft finger was shown to achieve tip rotation of up to 219 deg under 29 kPa actuation pressure. Finally, the potential capability of the bending-twisting soft fingers was verified through applications like screwing and object grasping.

Stretchable, self-adhesive, conductive, anti-freezing sodium polyacrylate-based composite hydrogels for wearable flexible strain sensors

The vigorous development of flexible sensors, wearable electronic devices, and human-computer interaction techniques has promoted the construction of flexible, stretchable, and conductive hydrogels. However, due to the lack of self-adhesion and environmental adaptability, these hydrogels still face huge challenges in accurately and stably monitoring human motions as flexible sensors. In this paper, a multifunctional hydrogel of poly(sodium polyacrylate-dopamine based methylacrylamide)/polyvinyl alcohol (i.e., P(AAS-DAAM)/PVA) with the properties of stretchable, self-adhesive, conductive, and anti-freezing was synthetized by introducing methacrylic acid modified dopamine into sodium polyacrylate crosslinked network, and combine with a physical cross-linked network of the polyvinyl alcohol. The hydrogel exhibits excellent stretchability (>1000%), the higher conductivity (0.038 ± 0.003 S·cm−1), good frost resistance (−30°C) and excellent adhesion (419.3 ± 5.95 N/m) and remarkable biocompatibility (relative cell viability up to 132 ± 2.63%). The results indicate that P(AAS-DAAM)/PVA hydrogel can be used as a flexible sensor. Moreover, P(AAS-DAAM)/PVA-based strain sensor not only can stably and repeatedly monitor the changes of different strains (50% ~ 200%) with high sensitivity (GF = 1.65), but also stable and accurate monitoring capabilities for large joint bending (fingers, wrists, elbows, knees) or small physical (swallowing, speaking) activities. This hydrogel preparation strategy strongly promotes the development of new multifunctional hydrogels and hydrogel-based flexible sensors and other equipment to a new step.

Maneuver and formation control of a pair of soft pneumatic bending fingers by a cooperative strategy for planar in-hand object manipulation

In this paper, we seek performing dynamic in-hand object manipulation with two-segmented soft fingers in 2-D plane. Thereby, after the dynamic behavior of the soft fingers was defined, we evaluate the influence of external tip force on the finger. It is shown that the tip position error, under the effect of tip force, can be represented by uncertainties in kinematic parameters of the finger. As a result, we design a sliding-adaptive controller with compensation of kinematic uncertainties to fulfill our expectation that is controlling the tip position of the finger in vertical plane while interacting with the environment. Finally, inspired by the way that human fingers manipulate an object, a cooperative control system for manipulation is proposed which incorporates the states and tip positions of the fingers in its feedback signal. Combination of this controller with the adaptive control system yields more promising results than does the PID controller. In order to evaluate performance of the proposed controller, Simulation results for manipulation of a cubic rigid object are demonstrated.

Highly Durable and Stretchable Ti3C2Tx/PPy‐Fabric‐Based Strain Sensor for Human‐Motion Detection

AbstractFlexible, stretchable, and wearable fabric strain sensors can easily detect human motions and monitor human health, but their utility is limited by poor stability and sensing performance. The stability and sensing performances of the fabric strain sensors are invariably determined by the fabric and conductive materials. Here, a Ti3C2Tx/polypyrrole (PPy) nylon strain sensor is fabricated using a facile one‐step polymerization of pyrrole (Py) monomers in the presence of Ti3C2Txsuspension at 0 °C. The Ti3C2Txnanosheets/PPy nanospheres heterostructure adhered to the nylon substrate inhibits mutual agglomeration and stacking, which provides more electron transfer pathways. The nylon substrate and two conductive materials endow the sensor with excellent stretchability (50%), low resistance (80 Ω cm−1), fast response (40 ms), and recovery (70 ms), a wide sensing range (0–50%), and long‐term sensing function (2000 cycles). With these virtues, the prepared Ti3C2Tx/PPy nylon sensor can monitor human activities effectively, including joint bending (finger, elbow, and knee) and subtle motions (carotid pulse, slight pressing, and speaking vibrations). The flexible and highly conductive Ti3C2Tx/PPy strain sensor exhibits a promising sensing performance against the external strain, allowing it to be used in health‐care monitoring.

A time-independent deformer for elastic contacts

We present a purely geometric, time-independent deformer resolving local contacts between elastic objects, including self-collisions between adjacent parts of the same object that often occur in character skinning animation. Starting from multiple meshes in intersection, our deformer first computes the parts of the surfaces remaining in contact, and then applies a procedural displacement with volume preservation. Although our deformer processes each frame independently, it achieves temporally continuous deformations with artistic control of the bulge through few pseudo-stiffness parameters. The plausibility of the deformation is further enhanced by anisotropically spreading the volume-preserving bulge. The result is a robust, real-time deformer that can handle complex geometric configurations such as a ball squashed by a hand, colliding lips, bending fingers, etc.

Wearable Triboelectric Strain-Insensitive Pressure Sensors Based on Hierarchical Superposition Patterns.

Recently, wearable triboelectric sensors capable of self-powering, which can be widely used in artificial skin and robotics, have received much attention. Herein, we develop a stretchable triboelectric pressure sensor with a new pattern by superimposing two patterns using both polystyrene beads and UV-ozone treatment. This patterned structure works more sensitively to pressure than a general planar and one-kind patterned structure. The sensor is constructed by sandwiching styrene butadiene rubber (SBR) and poly(dimethylsiloxane) (PDMS). It demonstrates a high sensitivity of 0.078 kPa-1 (0-20 kPa), a low detection limit (1.2 kPa), and pressure sensitivity maintained under 40% strain. The detection behavior of the strain-insensitive triboelectric sensor against pressure is very consistent with the simulation based on the theory. In applications, we successfully detect various human motions, not only small motions such as bending fingers but also large motions such as standing up and raising arms.

Low‐Cost, Highly Sensitive, and Flexible Piezoresistive Pressure Sensor Characterized by Low‐Temperature Interfacial Polymerization of Polypyrrole on Latex Sponge

AbstractPiezoresistive pressure sensors based on sponge are widely concerned because of their wide strain range, convenient signal acquisition, and good compressibility, yet it is still a challenge to acquire sponge‐based pressure sensors with low cost and excellent sensing performance. Herein, low‐priced FeCl3.6H2O and pyrrole (Py) are dispersed in deionized water to form FeCl3.6H2O/Py solution. Commercial latex sponge is impregnated into this solution to prepare conductive polypyrrole/latex (PPy/latex) sponge through low‐temperature interfacial polymerization. The surface of latex sponge is covered by the micro‐wrinkled PPy, which endows the PPy/latex sponge with a certain electrical conductivity. The specific porous structure and high elasticity of the latex sponge are the basic conditions for PPy/latex sponge excellent piezoresistive behaviors. PPy/latex sponge based piezoresistive pressure sensor shows high sensitivity (0.084 kPa−1 at below 3.12 kPa), wider sensing range (0–85.0%) and long durability over 3800 s (1800 cycles). At the same time, the ability of the PPy/latex sponge based piezoresistive pressure sensor to monitor human movement has been successfully evaluated in some application scenarios, such as bending fingers, grabbing objects, tiptoe rising, and crouching.

Dupuytren's Contracture: The Readability of Online Information.

Dupuytren's contracture is a common hand pathology for which consultation and treatment are largely at the patient's discretion. The objective of this study was to evaluate the readability of current online patient information regarding Dupuytren's contracture. The largest public search engines (Google, Yahoo, and Bing) were queried using the search terms “Dupuytren's contracture,” “Dupuytren's disease,” “Viking's disease,” and “bent finger.” The first 30 unique websites by each search were analyzed and readability assessed using five established algorithms: Flesch Reading Ease, Gunning-Fog Index, Flesch–Kincaid Grade level, Coleman–Liau index, and Simple Measure of Gobbledygook grade level. Analysis of 73 websites demonstrated an average Flesch Reading Ease score of 48.6 ± 8.0, which corresponds to college reading level. The readability of websites ranged from 10.5 to 13.3 reading grade level. No article was written at or below the recommended sixth grade reading level. Information on the internet on Dupuytren's contracture is written at higher than recommended reading grade level. There is a need for high-quality patient information on Dupuytren's contracture at appropriate reading grade levels for patients of various health literacy backgrounds. Hospitals, universities, and academic organizations focused on the development of readable online information should consider patients’ input and preferences.

Variable stiffness soft pneumatic grippers augmented with active vacuum adhesion

Soft pneumatic grippers (SPGs), made of highly stretchable elastomer materials with internal fluidic channels, are a popular soft robotic gripping technology, and have been configured as soft bending fingers for passively compliant grasping applications. It is challenging, however, for current SPGs to grip both flat, concave, and convex surfaces. Controllable adhesion augmented SPGs are promising solutions. We aim to develop a composite gripper structure that could enable SPGs with the capability to lift flat, concave, and convex surfaces using pneumatic inputs only. To this end, we present PneuIVAVS, a layer-jamming induced active vacuum adhesion (VA) augmented and variable stiffness (VS) fiber-reinforced SPG. This integrated PneuIVAVS design has enabled the gripper to generate a VA force without the requirement that all suction units should work. Also, a VA force analytical model and a shape-locking model of the PneuIVAVS design were developed and experimentally validated. In addition, the PneuIVAVS gripper presented good performance on gripping both flat, concave and convex objects with a range of contacting areas. According to the load capacity test, the gripper could grasp a maximum of approximately 470 g, 683 g, and 268 g when handling flat, concave, and convex surfaces respectively. Besides, the gripper could grasp curved surfaces with a minimum radius of curvature between 30 and 40 mm. The PneuIVAVS concept, design, and results in this work have potential to promote the applications of SPGs and VA grippers in various material handling and robotics tasks.

Developing a hand sizing system for a hand exoskeleton device based on the Kansei Engineering method

This study aimed to identify the customers’ requirements for a hand rehabilitation exoskeleton device using the Kansei Engineering approach and propose improvements. The Kansei Engineering approach was used to extract the design attributes for a hand rehabilitation exoskeleton device by conducting an in-depth interview with 3 physical therapists. The Kano questionnaire survey investigated 25 participants with hand rehabilitation experience. The Kano classification results found three attractive factors and corresponded it to the design attributes of the evaluation grid method results that were suitable (size), flexible (controllability), and light (weight). The principal component analysis results indicated three components can be considered as the improvement categories; functions, structure-texture, and appearance of the hand exoskeleton device. The new functional and structural designs were proposed in a previous study. This study collects 110 male participants’ hand anthropometric data to establish a hand sizing system as a design improvement (suitable attribute). The 3D and manual measurements were obtained for 63 hand dimensions with an open palm posture. The 14 dorsal length dimensions with three bent finger postures were also manually measured. The results showed that the $${\text{MAD}}_{\text{Precision}}$$ (mean absolute difference) of 3D measurement is smaller than that of manual measurement, indicating better reproducibility of 3D scanning. The $${\text{MAD}}_{\text{Accuracy}}$$ of all dimensions are within the 1 mm of the referenced ISO 20685 criteria. Significant differences were found in the 14 dorsal hand length, showing that databases should explicitly state the aspect (dorsal or palmar) where dimensions have been of measurement. The 77 hand dimensions were taken into consideration to develop a hand sizing system using the clustering results. The two-level self-organizing map method was performed and 3 handshape types and 8 sizes were extracted. The coverage rate of the sizing system was over 85%. These results provide useful information for designing and manufacturing for hand-related products.

Soft fiber-reinforced bending finger with three chambers actuated by ECF (electro-conjugate fluid) pumps

Fluidic elastomer actuators (FEAs) have been used for various purposes such as grippers, soft robots, artificial muscles etc. A major challenge for the FEAs is their big and cumbersome power sources, which include valves, regulators, hydraulic pumps and air cylinders. Therefore, we integrated an ECF jet generator (a hydraulic pressure source) into a soft fiber-reinforced bending tube with three chambers. ECF (electro-conjugate fluid) is a kind of functional and dielectric fluid, which can generate a strong and active ECF jet when a high DC voltage is applied to its corresponding anode & cathode in ECF. The ECF jet generator has three ECF pumps with three pairs of electrodes, namely, needle-ring electrodes, which are manufactured by machining. The flexible tube consists of three soft chambers fabricated by replicating the molds. The principle is that one chamber (two chambers) of the soft finger expands as the inner pressure is generated by the ECF pump and two other chambers (one chamber), acting as an ECF container, shrinks, which finally causes the finger to bend. We introduce two types of commonly used ECFs and investigate their impact on the soft fiber-reinforced bending finger. Then, we numerically simulate the pressure generated by the ECF generator and the displacement of the bending finger, which are validated by the experiments. Finally, we research the dynamic performance of the bending finger. The work contributes to the miniaturization of power sources in the field of soft robots with spatial motions and is also helpful for the development of other ECF-based soft robots.

The Death of a Master

The Death of a Master T. J. Stiles (bio) The swelling bulged out of the back of my hand in a symmetrical hemisphere, like a golf ball under the skin. I recognized it as a hematoma. It was a late summer day in 1986. I was twenty-two. I had practiced traditional Japanese karate for six years—time enough for an education in how the body bruises, balloons, and breaks. But it was my first day in this dojo, the Japan Karate Association of New York, on the fourth floor above the Fairway Supermarket on Seventy-Fourth Street and Broadway. After class I went to the instructor and asked if he had any chemical cold packs. His name was Masataka Mori—Mori Sensei to his students, then a hachidan, or eighth-degree black belt. A little shorter than my own 5′8″, he was a Japanese native with a square jaw, brief nose with flaring nostrils, and close-cut black hair. His limbs seemed disproportionately short for his torso, and he rolled up the cuffs of his do gi (or keiko gi), his crisp white cotton uniform. In the dojo his glare alternated between two states best described as partially unsheathed and dismembering. In contemporary photos he looks [End Page 34] remarkably young to me, though he was two months short of fifty-four, my age as I write this. He ignored my request and snatched up my fist in his left palm. He studied it briefly, raised his other hand, and smashed down the swelling with the knuckles of his bent fingers. It was so unexpected that I just stood in shock as pain shrieked up my arm. A doctor later characterized his novel treatment as “further traumatizing the damaged blood vessels.” Mori Sensei dismissed me without explanation. I wandered away, baffled. Thirty-two years later, on September 2, 2018, I received an e-mail from a friend in New York. Mori Sensei was “in grave condition,” he wrote. Old students were going to see him one last time. From my house in Berkeley, California, I reached out to his two daughters, Mayumi and Sayuri. They told me he was in home hospice. I feared I might be too late, that my visit would be a burden. I closed the door on my wife and two children, sat on my bed, and wept. I wept because he was a master—because he was my master. That’s difficult for me to write. I’m not naturally a follower. I was the kid who argued with the teacher. I was fired more than once because I was a difficult employee. It shocked my wife to hear me answer a call from Mori Sensei, to adopt a deferential tone I took with no one else. I couldn’t explain it to her then. I have trouble explaining it to myself now. ________ What is a master? I’m sure many karateka, practitioners of karate, have an opinion. As with all esoterica, the martial arts produce know-it-alls. Many genuinely know more about karate than I and are better at it. Making the answer more difficult: it’s diverse, too, less a single art than a cluster, all descended from secretive [End Page 35] Okinawan practices. Mine is Shotokan style, overseen by the Japan Karate Association, or JKA, a long-established institution headquartered in Tokyo. I have a godan, or fifth-degree black belt, as well as licenses as an instructor, rank examiner, and tournament judge. But I never studied in Japan, don’t speak the language, and have never given my full time to karate. I am not a master as surely as Mori Sensei was. Our intuitive answer begins with mastery itself—that is, with superlative skill. When I first saw him, though, his abilities did not seem apparent to me. He did not move with the particular feline grace or shocking speed that distinguishes later graduates of the instructor course in Tokyo—though, of course, I never saw him when he was young. I thought his techniques looked old-fashioned, heavy and deep; after all, he began training at Takushoku University in 1950, a year after the...