Transforming the Anthropomorphic Passive Free-Flow Foot Prosthesis Into a Powered Foot Prosthesis With Intuitive Control and Sensation (Bionic FFF).

INTRODUCTION: Approximately 89% of all service members with amputations do not return to duty. Restoring intuitive neural control with somatosensory sensation is a key to improving the safety and efficacy of prosthetic locomotion. However, natural somatosensory feedback from lower-limb prostheses has not yet been incorporated into any commercial prostheses. MATERIALS AND METHODS: We developed a neuroprosthesis with intuitive bidirectional control and somatosensation and evoking phase-dependent locomotor reflexes, we aspire to significantly improve the prosthetic rehabilitation and long-term functional outcomes of U.S. amputees. We implanted the skin and bone integrated pylon with peripheral neural interface pylon into the cat distal tibia, electromyographic electrodes into the residual gastrocnemius muscle, and nerve cuff electrodes on the distal tibial and sciatic nerves. Results. The bidirectional neural interface that was developed was integrated into the existing passive Free-Flow Foot and Ankle prosthesis, WillowWood, Mount Sterling, OH. The Free-Flow Foot was chosen because it had the highest Index of Anthropomorphicity among lower-limb prostheses and was the first anthropomorphic prosthesis brought to market. Conclusion. The cats walked on a treadmill with no cutaneous feedback from the foot in the control condition and with their residual distal tibial nerve stimulated during the stance phase of walking.

Adaptative machine vision with microsecond-level accurate perception beyond human retina.

Visual adaptive devices have potential to simplify circuits and algorithms in machine vision systems to adapt and perceive images with varying brightness levels, which is however limited by sluggish adaptation process. Here, the avalanche tuning as feedforward inhibition in bionic two-dimensional (2D) transistor is proposed for fast and high-frequency visual adaptation behavior with microsecond-level accurate perception, the adaptation speed is over 104 times faster than that of human retina and reported bionic sensors. As light intensity changes, the bionic transistor spontaneously switches between avalanche and photoconductive effect, varying responsivity in both magnitude and sign (from 7.6 × 104 to -1 × 103 A/W), thereby achieving ultra-fast scotopic and photopic adaptation process of 108 and 268 µs, respectively. By further combining convolutional neural networks with avalanche-tuned bionic transistor, an adaptative machine vision is achieved with remarkable microsecond-level rapid adaptation capabilities and robust image recognition with over 98% precision in both dim and bright conditions.

A Zero-Voltage-Writing Artificial Nervous System Based on Biosensor Integrated on Ferroelectric Tunnel Junction.

The artificial nervous system proves the great potential for the emulation of complex neural signal transduction. However, a more bionic system design for bio-signal transduction still lags behind that of physical signals, and relies on additional external sources. Here, this work presents a zero-voltage-writing artificial nervous system (ZANS) that integrates a bio-source-sensing device (BSSD) for ion-based sensing and power generation with a hafnium-zirconium oxide-ferroelectric tunnel junction (HZO-FTJ) for the continuously adjustable resistance state. The BSSD can use ion bio-source as both perception and energy source, and then output voltage signals varied with the change of ion concentrations to the HZO-FTJ, which completes the zero-voltage-writing neuromorphic bio-signal modulation. In view of in/ex vivo biocompatibility, this work shows the precise muscle control of a rabbit leg by integrating the ZANS with a flexible nerve stimulation electrode. The independence on external source enhances the application potential of ZANS in robotics and prosthetics.

A Bionic Localization Memristive Circuit Based on Spatial Cognitive Mechanisms of Hippocampus and Entorhinal Cortex.

In this article, a bionic localization memristive circuit is proposed, which mainly consists of head direction cell module, grid cell module, place cell module and decoding module. This work modifies the two-dimensional Continuous Attractor Network (CAN) model of grid cells into two one-dimensional models in X and Y directions. The head direction cell module utilizes memristors to integrate angular velocity and represents the real orientation of an agent. The grid cell module uses memristors to sense linear velocity and orientation signals, which are both self-motion cues, and encodes the position in space by firing in a periodic mode. The place cell module receives the grid cell module's output and fires in a specific position. The decoding module decodes the angle or place information and transfers the neuron state to a 'one-hot' code. This proposed circuit completes the localizing task in space and realizes in-memory computing due to the use of memristors, which can shorten the execution time. The functions mentioned above are implemented in LTSPICE. The simulation results show that the proposed circuit can realize path integration and localization. Moreover, it is shown that the proposed circuit has good robustness and low area overhead. This work provides a possible application idea in a prospective robot platform to help the robot localize and build maps.

Visualized in-sensor computing.

In artificial nervous systems, conductivity changes indicate synaptic weight updates, but they provide limited information compared to living organisms. We present the pioneering design and production of an electrochromic neuromorphic transistor employing color updates to represent synaptic weight for in-sensor computing. Here, we engineer a specialized mechanism for adaptively regulating ion doping through an ion-exchange membrane, enabling precise control over color-coded synaptic weight, an unprecedented achievement. The electrochromic neuromorphic transistor not only enhances electrochromatic capabilities for hardware coding but also establishes a visualized pattern-recognition network. Integrating the electrochromic neuromorphic transistor with an artificial whisker, we simulate a bionic reflex system inspired by the longicorn beetle, achieving real-time visualization of signal flow within the reflex arc in response to environmental stimuli. This research holds promise in extending the biomimetic coding paradigm and advancing the development of bio-hybrid interfaces, particularly in incorporating color-based expressions.

Steering Muscle-Based Bio-Syncretic Robot Through Bionic Optimized Biped Mechanical Design.

Bio-syncretic robots consisting of artificial structures and living muscle cells have attracted much attention owing to their potential advantages, such as high drive efficiency, miniaturization, and compatibility. Motion controllability, as an important factor related to the main performance of bio-syncretic robots, has been explored in numerous studies. However, most of the existing bio-syncretic robots still face challenges related to the further development of steerable kinematic dexterity. In this study, a bionic optimized biped fully soft bio-syncretic robot actuated by two muscle tissues and steered with a direction-controllable electric field generated by external circularly distributed multiple electrodes has been developed. The developed bio-syncretic robot could realize wirelessly steerable motion and effective transportation of microparticle cargo on artificial polystyrene and biological pork tripe surfaces. This study may provide an effective strategy for the development of bio-syncretic robots and other related studies, such as nonliving soft robot design and muscle tissue engineering.

Fast-Swimming Soft Robotic Fish Actuated by Bionic Muscle.

Soft underwater swimming robots actuated by smart materials have unique advantages in exploring the ocean, such as low noise, high flexibility, and friendly environment interaction ability. However, most of them typically exhibit limited swimming speed and flexibility due to the inherent characteristics of soft actuation materials. The actuation method and structural design of soft robots are key elements to improve their motion performance. Inspired by the muscle actuation and swimming mechanism of natural fish, a fast-swimming soft robotic fish actuated by a bionic muscle actuator made of dielectric elastomer is presented. The results show that by controlling the two independent actuating units of a biomimetic actuator, the robotic fish can not only achieve continuous C-shaped body motion similar to natural fish but also have a large bending angle (maximum unidirectional angle is about 40°) and thrust force (peak thrust is about 14 mN). In addition, the coupling relationship between the swimming speed and actuating parameters of the robotic fish is established through experiments and theoretical analysis. By optimizing the control strategy, the robotic fish can demonstrate a fast swimming speed of 76 mm/s (0.76 body length/s), which is much faster than most of the reported soft robotic fish driven by nonbiological soft materials that swim in body and/or caudal fin propulsion mode. What's more, by applying programmed voltage excitation to the actuating units of the bionic muscle, the robotic fish can be steered along specific trajectories, such as continuous turning motions and an S-shaped routine. This study is beneficial for promoting the design and development of high-performance soft underwater robots, and the adopted biomimetic mechanisms, as well as actuating methods, can be extended to other various flexible devices and soft robots.

Multicenter, Randomized Trial of a Bionic Pancreas in Type 1 Diabetes.

BACKGROUND: Currently available semiautomated insulin-delivery systems require individualized insulin regimens for the initialization of therapy and meal doses based on carbohydrate counting for routine operation. In contrast, the bionic pancreas is initialized only on the basis of body weight, makes all dose decisions and delivers insulin autonomously, and uses meal announcements without carbohydrate counting. METHODS: In this 13-week, multicenter, randomized trial, we randomly assigned in a 2:1 ratio persons at least 6 years of age with type 1 diabetes either to receive bionic pancreas treatment with insulin aspart or insulin lispro or to receive standard care (defined as any insulin-delivery method with unblinded, real-time continuous glucose monitoring). The primary outcome was the glycated hemoglobin level at 13 weeks. The key secondary outcome was the percentage of time that the glucose level as assessed by continuous glucose monitoring was below 54 mg per deciliter; the prespecified noninferiority limit for this outcome was 1 percentage point. Safety was also assessed. RESULTS: A total of 219 participants 6 to 79 years of age were assigned to the bionic-pancreas group, and 107 to the standard-care group. The glycated hemoglobin level decreased from 7.9% to 7.3% in the bionic-pancreas group and did not change (was at 7.7% at both time points) in the standard-care group (mean adjusted difference at 13 weeks, -0.5 percentage points; 95% confidence interval [CI], -0.6 to -0.3; P<0.001). The percentage of time that the glucose level as assessed by continuous glucose monitoring was below 54 mg per deciliter did not differ significantly between the two groups (13-week adjusted difference, 0.0 percentage points; 95% CI, -0.1 to 0.04; P<0.001 for noninferiority). The rate of severe hypoglycemia was 17.7 events per 100 participant-years in the bionic-pancreas group and 10.8 events per 100 participant-years in the standard-care group (P = 0.39). No episodes of diabetic ketoacidosis occurred in either group. CONCLUSIONS: In this 13-week, randomized trial involving adults and children with type 1 diabetes, use of a bionic pancreas was associated with a greater reduction than standard care in the glycated hemoglobin level. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases and others; ClinicalTrials.gov number, NCT04200313.).

Characterization of Patients With Obstructed Defecation and Slow Transit Constipation With a Simulated Stool.

INTRODUCTION: Defecatory disorders including obstructed defecation (OD) are currently diagnosed using specialized investigations including anorectal manometry and the balloon expulsion test. Recently, we developed a simulated stool named Fecobionics that provides a novel type of pressure measurements and analysis. The aim was to study OD phenotypes compared with slow transit constipation (STC) patients and normal subjects (NS). METHODS: Fecobionics expulsion parameters were assessed in an interventional study design. The Fecobionics device contained pressure sensors at the front, rear, and inside a bag. All constipation patients had colon transit study, defecography, anorectal manometry, and balloon expulsion test performed. The Fecobionics bag was distended in the rectum until desire-to-defecate in 26 OD compared with 8 STC patients and 10 NS. Rear-front pressures (preload-afterload parameters) and defecation indices (DIs) were compared between groups. RESULTS: The Wexner constipation scoring system score was 13.8 ± 0.9 and 14.6 ± 1.5 in the OD and STC patients (P > 0.5). The median desire-to-defecate volume was 80 (quartiles 56-80), 60 (54-80), and 45 (23-60) mL in OD, STC, and NS, respectively (P < 0.01). The median expulsion duration was 37 (quartiles 15-120), 6 (3-11), and 11 (8-11) seconds for the 3 groups (P < 0.03). Fecobionics rear-front pressure diagrams demonstrated clockwise loops with distinct phenotype differences between OD and the other groups. Most DIs differed between OD and the other groups, especially those based on the anal afterload reflecting the nature of OD constipation. Several OD subtypes were identified. DISCUSSION: Fecobionics obtained novel pressure phenotypes in OD patients. DIs showed pronounced differences between groups. Larger studies are needed on OD subtyping.

Bionic intelligent soft actuators: high-strength gradient intelligent hydrogels with diverse controllable deformations and movements.

A series of novel nanofibrillated cellulose (NFC) reinforced gradient intelligent hydrogels with high response rate, multiple response patterns and diversified self-driven functions were successfully prepared. Based on the effect of the hydroxide radical of NFC on the addition reaction, and on the dehydration synthesis, the variation of NFC significantly regulated the gradient structure of the intelligent hydrogels. In addition to the infiltration property of graphene oxide (GO), reinforcement of NFC enhanced the crosslinking density and Young's modulus, which built a relationship between material characteristics and near infrared laser response rate. Intelligent hydrogel actuators realized bending deformation, curling deformation, switching movements and obstacle avoidance movements. The hydrogels with high Young's modulus exhibited relatively low self-driven rates and efficiency. The self-driven mechanisms of NFC reinforced gradient intelligent hydrogels were revealed effectively by constructing the mathematical relationship curvature variation, bending degree, deformation displacement, material characteristics and incentive intensity. The investigation showed a new path for the combination of mechanical property, intelligent property and functional property of intelligent hydrogels in a bionic soft robot and health engineering.

Bionic Detectors Based on Low-Bandgap Inorganic Perovskite for Selective NIR-I Photon Detection and Imaging.

Fluorescence imaging with photodetectors (PDs) toward near-infrared I (NIR-I) photons (700-900 nm), the so-called "optical window" in organisms, has provided an important path for tracing biological processes in vivo. With both excitation photons and fluorescence photons in this narrow range, a stringent requirement arises that the fluorescence signal should be efficiently differentiated for effective sensing, which cannot be fulfilled by common PDs with a broadband response such as Si-based PDs. In this work, delicate optical microcavities are designed to develop a series of bionic PDs with selective response to NIR-I photons, the merits of a narrowband response with a full width at half maximum (FWHM) of <50 nm, and tunability to cover the NIR-I range are highlighted. Inorganic halide perovskite CsPb0.5 Sn0.5 I3 is chosen as the photoactive layer with comprehensive bandgap and film engineering. As a result, these bionic PDs offer a signal/noise ratio of ≈106 , a large bandwidth of 543 kHz and an ultralow detection limit of 0.33 nW. Meanwhile, the peak responsivity (R) and detectivity (D*) reach up to 270 mA W-1 and 5.4 × 1014 Jones, respectively. Finally, proof-of-concept NIR-I imaging using the PDs is demonstrated to show great promise in real-life application.

Self-Healable Conductive Nanocellulose Nanocomposites for Biocompatible Electronic Skin Sensor Systems.

Electronic skins are developed for applications such as biomedical sensors, robotic prosthetics, and human-machine interactions, which raise the interest in composite materials that possess both flexibility and sensing properties. Polypyrrole-coated cellulose nanocrystals and cellulose nanofibers were prepared using iron(III) chloride (FeCl3) oxidant, which were used to reinforce polyvinyl alcohol (PVA). The combination of weak H-bonds and iron coordination bonds and the synergistic effect of these components yielded self-healing nanocomposite films with robust mechanical strength (409% increase compared to pure PVA and high toughness up to 407.1%) and excellent adhesion (9670 times greater than its own weight) to various substrates in air and water. When damaged, the nanocomposite films displayed good mechanical (72.0-76.3%) and conductive (54.9-91.2%) recovery after a healing time of 30 min. More importantly, the flexible nanocomposites possessed high strain sensitivity under subtle strains (<48.5%) with a gauge factor (GF) of 2.52, which was relatively larger than the GF of ionic hydrogel-based skin sensors. These nanocomposite films possessed superior sensing performance for real-time monitoring of large and subtle human motions (finger bending motions, swallowing, and wrist pulse); thus, they have great potentials in health monitoring, smart flexible skin sensors. and wearable electronic devices.

Differences in the impedance of cochlear implant devices within 24 hours of their implantation.

Cochlear implantation is a surgical procedure, which is performed on severely hearing-impaired patients. Impedance field telemetry is commonly used to determine the integrity of the cochlear implant device during and after surgery. At the Department of Otolaryngology, Cheng Hsin General Hospital (Taipei, Taiwan), the cochlear implant devices are switched on within 24 hours of their implantation. In the present study, the impedance changes of Advanced Bionics™ cochlear implant devices were compared with previous studies and other devices. The aim was to confirm previous hypotheses and to explore other potential associated factors that could influence impedance following cochlear implantation. The current study included 12 patients who underwent cochlear implantation at Cheng Hsin General Hospital with Advanced Bionics cochlear implant devices. The cochlear devices were all switched on within 24 hours of their implantation. The impedance was measured and compared across all contact channels of the electrode, both intra-operatively and post-operatively. The intra-operative impedance was compared with the switch-on impedance (within 24 hours of the cochlear implantation); the impedance was notably increased for all contact channels at switch-on. Of the 16 channels examined, 4 channels had a significant increase in impedance between the intra-operative measurement and the switch-on measurement. To the best of our knowledge, the impedance of a cochlear implant device can be affected by the diameter of the electrode, the position of the electrode arrays in the scala tympani, sheath formation and fibrosis surrounding the electrode after implantation and electrical stimulation during or after surgery. When the results of the current study were compared with previous studies, it was found that the impedance changes were opposite to that of Cochlear™ implant devices. This may be explained by the position of the electrode arrays, sheath formation, the blow-out effect and differences in electrical stimulation.

Optoelectronic resistive random access memory for neuromorphic vision sensors.

Neuromorphic visual systems have considerable potential to emulate basic functions of the human visual system even beyond the visible light region. However, the complex circuitry of artificial visual systems based on conventional image sensors, memory and processing units presents serious challenges in terms of device integration and power consumption. Here we show simple two-terminal optoelectronic resistive random access memory (ORRAM) synaptic devices for an efficient neuromorphic visual system that exhibit non-volatile optical resistive switching and light-tunable synaptic behaviours. The ORRAM arrays enable image sensing and memory functions as well as neuromorphic visual pre-processing with an improved processing efficiency and image recognition rate in the subsequent processing tasks. The proof-of-concept device provides the potential to simplify the circuitry of a neuromorphic visual system and contribute to the development of applications in edge computing and the internet of things.

Rhinophore bio-inspired stretchable and programmable electrochemical sensor.

Rhinophore, a bio-chemical sensory organ with soft and stretchable/retractable features in many marine molluscs species, exhibits tunable chemosensory abilities in terms of far/near-field chemical detection and molecules' source orientation. However, existing artificial bio-chemical sensors cannot provide tunable modality sensing. Inspired by the anatomical units (folded sensory epithelium) and the functions of a rhinophore, this work introduces a stretchable electrochemical sensor that offers a programmable electro-catalytic performance towards glucose based on the fold/unfold regulation of the gold nanomembrane on an elastic fiber. Geometrical design rationale and covalent bonding strategy are used to realize the robust mechanical and electrical stability of this stretchable bionic sensor. Electrochemical tests demonstrated that the sensitivities of the as-prepared bionic sensor exhibit a linear relationship with its strain states from 0% to 150%. Bio-inspired sensory functions are tested by regulating the strain of the bionic sensor. The sensor achieves a sensitivity of 195.4 µA mM-1 in a low glucose concentration range of 8-206 µM at 150% strain for potentially far-field chemical detection, and a sensitivity of 14.2 µA mM-1 in a high concentration range of 10-100 mM at 0% strain for near-field chemical detection. Moreover, the bionic sensor performs the detection while extending its length can largely enhance the response signal, which is used to distinguish the molecules' source direction. This proposed bionic sensor can be useful in wearable devices, robotics and bionics applications which require diverse modality sensing and smart chemical tracking system.

Electronic Decay Length in a Protein Molecule.

Antibodies have two identical binding domains and can therefore form a well-defined conducting bridge by binding a pair of electrodes functionalized with an epitope. The conductance measured between these two fixed points on the antibody does not change with the size of the electrode gap. A second conduction path is via one specific attachment to an epitope and a second nonspecific attachment to the surface of the antibody. In this case, the conductance does change with gap size, yielding an estimated electronic decay length >6 nm, long enough that it is not possible to distinguish between an exponential or a hyperbolic distance dependence. This decay length is substantially greater than that measured for hopping transport in an organic molecular wire.

High-Load Soft Grippers Based on Bionic Winding Effect.

The improvement of the load capacity of soft grippers has always been a challenge. To tackle this load capacity challenge, this work presents four novel types of high-load (HL) soft grippers that are bioinspired by bionic winding models. The winding models are found commonly in many animals and plants, where different winding patterns are used to grip different objects. Inspired by the winding models, we design four bionic winding structures that are driven by pneumatic artificial muscles (PAMs), and then four HL soft grippers are formed out of the winding structures. The inner cavities of the HL soft grippers contract after the PAMs are inflated, which enables objects to be wrapped to achieve gripping. Compared with most existing soft grippers, the HL soft grippers have a higher load capacity, and they can also grip various objects that have different shapes and stiffnesses without damaging them. In addition, in man-machine collaboration, operators can be in direct contact with them without being hurt. Our study helps lay the foundation for engineered systems with bionic winding structures.

Fecobionics: A Novel Bionics Device for Studying Defecation.

During defecation, solid, semisolid or liquid stools are eliminated via the anus in a complex physiological process. Up to 25% of the population are affected by anorectal disorders that are poorly recognized and treated. We developed a new bionics device, a simulated stool named Fecobionics, to replace several current tests of anorectal function. Fecobionics was developed to simulate the defecation process that depends on rectal forces, the anorectal size angle, and anorectal size and sensitivity. Fecobionics provided axial pressure signatures, measurement of bending (anorectal angle) and geometric mapping in a single examination. It had the consistency and shape of normal stool. The device had a soft core with embedded electronics and a bag for distension. The paper describes the device development and validation. Furthermore, data were obtained in preliminary experiments in pigs, healthy human subjects and patients with focus on four important features of the system, i.e. measurements of pressure signatures, bending characteristics, impedance measurements and data transmission. Accurate pressure and orientation data as well as geometric profiles were successfully obtained on the bench as well as in vivo in pigs and human subjects during defecation. Fecobionics is a novel technology imitating defecation. The clinical future ultimately depends on its ability to impact on daily treatment of anorectal disorders. A potential long-term clinical application is use of the device for biofeedback training for dyssynergic defecation.