Unfolding Orthogonal Polyhedra with Quadratic Refinement: The Delta-Unfolding Algorithm

We show that every orthogonal polyhedron homeomorphic to a sphere can be unfolded without overlap while using only polynomially many (orthogonal) cuts. By contrast, the best previous such result used exponentially many cuts. More precisely, given an orthogonal polyhedron with n vertices, the algorithm cuts the polyhedron only where it is met by the grid of coordinate planes passing through the vertices, together with Theta(n^2) additional coordinate planes between every two such grid planes.Comment: 15 pages, 10 figure

Haptic wearables as sensory replacement, sensory augmentation and trainer - a review

Sensory impairments decrease quality of life and can slow or hinder rehabilitation. Small, computationally powerful electronics have enabled the recent development of wearable systems aimed to improve function for individuals with sensory impairments. The purpose of this review is to synthesize current haptic wearable research for clinical applications involving sensory impairments. We define haptic wearables as untethered, ungrounded body worn devices that interact with skin directly or through clothing and can be used in natural environments outside a laboratory. Results of this review are categorized by degree of sensory impairment. Total impairment, such as in an amputee, blind, or deaf individual, involves haptics acting as sensory replacement; partial impairment, as is common in rehabilitation, involves haptics as sensory augmentation; and no impairment involves haptics as trainer. This review found that wearable haptic devices improved function for a variety of clinical applications including: rehabilitation, prosthetics, vestibular loss, osteoarthritis, vision loss and hearing loss. Future haptic wearables development should focus on clinical needs, intuitive and multimodal haptic displays, low energy demands, and biomechanical compliance for long-term usage

Ingestible, controllable, and degradable origami robot for patching stomach wounds

© 2016 IEEE.Developing miniature robots that can carry out versatile clinical procedures inside the body under the remote instructions of medical professionals has been a long time challenge. In this paper, we present origami-based robots that can be ingested into the stomach, locomote to a desired location, patch a wound, remove a foreign body, deliver drugs, and biodegrade. We designed and fabricated composite material sheets for a biocompatible and biodegradable robot that can be encapsulated in ice for delivery through the esophagus, embed a drug layer that is passively released to a wounded area, and be remotely controlled to carry out underwater maneuvers specific to the tasks using magnetic fields. The performances of the robots are demonstrated in a simulated physical environment consisting of an esophagus and stomach with properties similar to the biological organs

Development of a High Intensity Neutron Source at the European Spallation Source: The HighNESS project

The European Spallation Source (ESS), presently under construction in Lund, Sweden, is a multidisciplinary international laboratory that will operate the world's most powerful pulsed neutron source. Supported by a 3M Euro Research and Innovation Action within the EU Horizon 2020 program, a design study (HighNESS) is now underway to develop a second neutron source below the spallation target. Compared to the first source, located above the spallation target and designed for high cold and thermal brightness, the new source will provide higher intensity, and a shift to longer wavelengths in the spectral regions of cold (2 /- 20 {\AA}), very cold (VCN, 10 /- 120 {\AA}), and ultra cold (UCN, > 500 {\AA}) neutrons. The core of the second source will consist of a large liquid deuterium moderator to deliver a high flux of cold neutrons and to serve secondary VCN and UCN sources, for which different options are under study. The features of these new sources will boost several areas of condensed matter research and will provide unique opportunities in fundamental physics. Part of the HighNESS project is also dedicated to the development of future instruments that will make use of the new source and will complement the initial suite of instruments in construction at ESS. The HighNESS project started in October 2020. In this paper, the ongoing developments and the results obtained in the first year are described.Comment: 10 pages, 10 figures, 14th International Topical Meeting on Nuclear Applications of Accelerators, November 30 to December 4, 2021, Washington, D

A physical soft tissue growth simulator for implantable robotic devices

In the development of surgical technologies, one of the challenges in their initial validation has been the creation of accurate bench-top tissue phantoms. Tissue phantoms made of elastomeric material have fixed mechanical properties and are not able to increase in size, so they cannot mimic growth process or change in mechanical properties of their real counterparts. In this work we present a novel real-time soft tissue simulator aimed at testing the in vivo dynamic behavior of robotic implants. The simulator is capable of reproducing mechanical properties of the biological tissue, e.g. viscoelasticity, as well as its metabolism, being able to grow up to 260 mm. A control strategy based on impedance control enables the simulation of changing mechanical properties in real-time, in order to recreate conditions such as fibrosis or tissue scarring. We finally show the platform in use with a soft implant. The electric actuation in conjunction with the 500 Hz control loop frequency guarantees fast and accurate response. We believe our platform has the potential to reduce the need for in vivo preclinical studies and shorten the path to clinical experimentation

Data-driven and compliance-based fault-tolerance for a flexible and extendable robotic implant coupled to a growing tissue

Robotic implants for real-time and long-term monitoring and therapies are being researched and could open new frontiers in the medical field. For these devices to see widespread adoption, though, key challenges still need to be overcome, including reliability. Over the years, many computational techniques have been developed to impart fault-tolerance to robots and industrial plants. However, the application of these approaches to robotic implants is still challenging, due to the lack of information about the complex behavior of soft tissue (e.g. growth, viscoelasticity) and robot-tissue interaction. In this letter, a novel fault detection framework for a flexible extendable robotic implant is presented. Based on Canonical Correlation Analysis, the approach exploits the flexibility of the robot to extrapolate information for fault identification purposes. The experiments are conducted with a soft tissue simulator, which can emulate the viscoelastic properties of tissue as well as its growth, providing a realistic testing platform. The experiments prove the reliability of the flexible extendable robotic implant and its robustness to system-level external disturbances. Long-term tests are also presented, where the implant extends 80 mm, to its full length, counteracting simulated hardware faults over a 24-hour period, and provide a promising basis for future in-vivo trials

Fault tolerant control in shape-changing internal robots

It is known that the interior of the human body is one of the most adverse environments for a foreign body, such as an in-vivo robot, and vice-versa. As robots operating in-vivo are increasingly recognized for their capabilities and potential for improved therapies, it is important to ensure their safety, especially for long term treatments when little supervision can be provided. We introduce an implantable robot that is flexible, extendable and symmetric, thus changing shape and size. This design allows the implementation of an effective fault tolerant control, with features such as physical polling for fault diagnosis, retraction and redundancy-based control switching at fault. We demonstrate the fault-tolerant capabilities for an implantable robot that elongates tubular tissues by applying tension to the tissue. In benchtop tests, we show a reduction of the fault risks by at least 83%. The study provides a valuable methodology to enhance safety and efficacy of implantable and surgical robots, and thus to accelerate their adoption

Design and development of a robotic bioreactor for in vitro tissue engineering

In this study, a novel robotic bioreactor is presented with capabilities of closed-loop control of force and displacement applied to a tissue scaffold and tissue scaffold stiffness calculation. These characteristics bring the potential of a robotic bioreactor that can optimize the mechanical properties of tissue constructs in order for them to match those of native tissues. Custom position and force control signals are designed to maintain a steady tensioning of the tissue scaffold while the latter one’s mechanical properties evolve in time. We propose a simple model to support the hypothesis that the stiffness of a cell-seeded scaffold increases over time, and thus force control signals need to be adjusted accordingly. The robotic bioreactor is able to measure the stiffness of a scaffold sample relatively accurately, with an average standard deviation of 0.2N/mm. The combination of accurate stiffness measurements and a closed-loop control system equips the robotic bioreactor with the fundamental requirements to achieve stiffness based force control in future in vitro experiments, and thus to a tissue-scaffold responsive technology for advanced tissue engineering

Characterization, simulation and control of a soft helical pneumatic implantable robot for tissue regeneration

Therapies for tissue repair and regeneration have remained sub-optimal, with limited approaches investigated to improve their effectiveness, dynamic and control response. We introduce a Soft Pneumatic Helically-Interlayered Actuator (SoPHIA) for tissue repair and regeneration of tubular tissues. The actuator features shape configurability in two and three dimensions for minimal or non-invasive in vivo implantation; multi-modal therapy to apply mechanical stimulation axially and radially, in accordance to the anatomy of tubular tissues; and anti-buckling structural strength. We present a model and characteristics of this soft actuator. SoPHIA reaches up to 36.3% of elongation with respect to its initial height and up to 7 N of force when pressurized at 38 kPa against anatomically-realistic spatial constraints. Furthermore, we introduce the capabilities of a physical in vivo simulator of biological tissue stiffness and growth, for the evaluation of the soft actuator in physiologically-relevant conditions. Lastly, we propose a model-based multi-stage control of the axial elongation of the actuator according to the tissue’s physiological response. SoPHIA has the potential to reduce the invasiveness of surgical interventions and increase the effectiveness in growing tissue due to its mechanically compliant, configurable and multi-modal design