Inflatable Chambers Research Articles

Design, fabrication and experiment of soft fingers with double-chamber based on layer jamming

PurposeThe purpose of this paper is to propose a casting process for the production of double-chamber soft fingers, which avoids the problems of air leakage and fracture caused by multistep casting. This proposed method facilitates the simultaneous casting of the inflation chamber and the jamming chamber.Design/methodology/approachAn integrated molding technology based on the lost wax casting method is proposed for the manufacture of double-chamber soft fingers. The solid wax core is assembled with the mold, and then liquid silicone rubber is injected into it. After cooling and solidification, the mold is stripped off and heated in boiling water, so that the solid wax core melts and precipitates, and the integrated soft finger is obtained.FindingsThe performance and fatigue tests of the soft fingers produced by the proposed method have been carried out. The results show that the manufacturing method can significantly improve the fatigue resistance and stability of the soft fingers, while also avoiding the problems such as air leakage and cracking.Originality/valueThe improvement of the previous multistep casting method of soft fingers is proposed, and the integrated molding manufacturing method is proposed to avoid the problems caused by secondary bonding.

Transcutaneous oximetry values in chronic ulcer patients during Hyperbaric treatment at 1.4 ATA compared to 2 ATA

Chronic wounds have a significant impact on a patient’s quality of life. Different pathologies, such as poor blood supply and tissue breakdown, may lead to inadequate oxygenation of the wound. Hyperbaric oxygen (HBO2 ) is a widely used treatment for an increasing number of medical practices. A new so-called “hyperbaric treatment” trend has emerged. The use of low-pressure, soft-sided, or inflatable chambers represents a growing trend in hyperbaric medicine. Used in professional settings as well as directly marketed to individuals for home use, they are promoted as equivalent to clinical hyperbaric treatments provided in medical centers. However, these chambers are pressurized to 1.3 atmospheres absolute (ATA) on either air or with an oxygen concentrator, both generate oxygen partial pressures well below those used in approved hyperbaric centers for UHMS-approved indications. A total of 130 consecutive patients with chronic ulcers where tested. TcPO2 was measured near the ulcer area while the patient was breathing 100% O2 at 1.4 ATA for five and 10 minutes. The average TcPO2 at 1.4 ATA after 10 minutes of O2 breathing was 161 mmHg (1-601 mmHg, standard deviation 137.91), compared to 333 mmHg in 2 ATA (1-914±232.56), p < 0.001). Each electrode tested was also statistically significant, both after five minutes of O2 breathing and after 10 minutes. We have not found evidence supporting the claim that 1.4 ATA treatment can benefit a chronic ulcer patient. The field of HBO2 is constantly evolving. We have discovered new ways to treat previously incurable ailments. Nevertheless, it is important to note that new horizons must be examined scientifically, supported by evidence-based data. The actual effect of 1.4 ATA on many ailments is yet to be determined.

EEG Investigation on the Tactile Perceptual Performance of a Pneumatic Wearable Display of Softness

Multisensory human–machine interfaces for virtual- or augmented-reality systems are lacking wearable actuated devices that can provide users with tactile feedback on the softness of virtual objects. They are needed for a variety of uses, such as medical simulators, tele-operation systems and tele-presence environments. Such interfaces require actuators that can generate proper tactile feedback, by stimulating the fingertips via quasi-static (non-vibratory) forces, delivered through a deformable surface, so as to control both the contact area and the indentation depth. The actuators should combine a compact and lightweight structure with ease and safety of use, as well as low costs. Among the few actuation technologies that can comply with such requirements, pneumatic driving appears to be one of the most promising. Here, we present an investigation on a new type of pneumatic wearable tactile displays of softness, recently described by our group, which consist of small inflatable chambers arranged at the fingertips. In order to objectively assess the perceptual response that they can elicit, a systematic electroencephalographic study was conducted on ten healthy subjects. Somatosensory evoked potentials (SEPs) were recorded from eight sites above the somatosensory cortex (Fc2, Fc4, C2 and C4, and Fc1, Fc3, C1 and C3), in response to nine conditions of tactile stimulation delivered by the displays: stimulation of either only the thumb, the thumb and index finger simultaneously, or the thumb, index and middle finger simultaneously, each repeated at tactile pressures of 10, 20 and 30 kPa. An analysis of the latency and amplitude of the six components of SEP signals that typically characterise tactile sensing (P50, N100, P200, N300, P300 and N450) showed that this wearable pneumatic device is able to elicit predictable perceptual responses, consistent with the stimulation conditions. This proved that the device is capable of adequate actuation performance, which enables adequate tactile perceptual performance. Moreover, this shows that SEPs may effectively be used with this technology in the future, to assess variable perceptual experiences (especially with combinations of visual and tactile stimuli), in objective terms, complementing subjective information gathered from psychophysical tests.

Flexible and Slim Device Switching Air Blowing and Suction by a Single Airflow Control

This study proposes a soft robotic device with a slim and flexible body that switches between air blowing and suction with a single airflow control. Suction is achieved by jet flow entraining surrounding air, and blowing is achieved by blocking and reversing jet flow. The thin and flexible flap gate enables the switching. Air flow is blocked while the gate is closed and passes through while the gate is open. The opening and closing of the flap gate are controlled by the expansion of the inflatable chambers installed near the gate. The extent of expansion is determined by the upstream static pressure. Therefore, the gate can be controlled by the input airflow rate. The dimensions of the flap gate are introduced as a design parameter, and we show that the parameter contributes to the blowing and suction capacities. We also experimentally demonstrate that the proposed device is available for a variable friction system and an end effector for picking up a thin object covered with dust.

Flexible and stable grasping by multi-jointed pneumatic actuator mimicking the human finger-impacts of structural parameters on performance

Most current pneumatic actuators, whether they have a single inflation chamber or multiple inflation chambers, are driven by a single air source, limiting their ability to complete precise and targeted manipulation. This paper describes a flexible pneumatic actuator with a three-chamber structure to mimic the motion of a human finger. Each chamber, which mimics the finger joint, is independently driven by a pressurized air source, making the finger flexible enough to grasp an object according to its shape. To achieve a more extensive deformation with lower pressure, the finite element method (FEM) was used to optimize and determine the structural parameters of the actuator. Actuators, both with and without fiber-reinforcement, were experimentally investigated to determine the bending performance of the artificial finger when pressurized individually or simultaneously. A three-finger gripper fabricated based on the multi-jointed pneumatic actuator successfully grasps various objects with higher contact area compared to previous designs, which achieves more stable grasping. The current actuator is flexible and stable enough to be used for a wide range of objects with different dimensions, shapes, and textures by controlling the various chambers.

Self-excited air flow passage changing device for periodic pressurization of soft robot

Recently pneumatic-driven soft robots have been widely developed. Usually, the operating principle of this robot is the inflation and deflation of elastic inflatable chambers by air pressure. Some soft robots need rapid and periodic inflation and deflation of their air chambers to generate continuous motion such as progress motion or rotational motion. However, if the soft robot needs to operate far from the air pressure source, long air tubes are required to supply air pressure to its air chambers. As a result, there is a large delay in supplying air pressure to the air chamber, and the motion of the robot slows down. In this paper, we propose a compact device that changes its airflow passages by self-excited motion generated by a supply of continuous airflow. The diameter and the length of the device are 20 and 50 mm, respectively, and can be driven in a small pipe. Our proposed in-pipe mobile robot is connected to the device and can move in a small pipe by dragging the device into it. To apply the device widely to other soft robots, we also discuss a method of adjusting the output pressure and motion frequency.

Self-Adaption Soft Sensor Array Design for sEMG Control

Myoelectric sensors are becoming indispensable to detect myoelectric signals and play a significant role in various applications. This article aims to propose a soft sensor array with inflatable chambers and 22 channels as a substitute for conventional disposable sensors. The new sensor is made of the soft material, which is Ecoflex00-50 and copper electrodes. sEMG signals of five gestures are collected under three kinds of sensors, which are the inflated, the uninflated, and the conventional disposable sensor, respectively. The correlation coefficients (up to 0.9), signal-noise ratio (up to 19dB), movement artifact signal, and motor unit action potential (MUAP) duration was calculated and analyzed to verify the performance of the soft sensor array. An improved method based on CNN is used to classify gestures, and the result is encouraging, which is 96.2%. The research results have supported that the inflated sensor can improve the signal quality and the classification accuracy, which can lay the foundation for the myoelectric sensor design research.

Lamina Cribrosa Capillaries Straighten as Intraocular Pressure Increases

PurposeThe purpose of this study was to visualize the lamina cribrosa (LC) capillaries and collagenous beams, measure capillary tortuosity (path length over straight end-to-end length), and determine if capillary tortuosity changes when intraocular pressure (IOP) increases.MethodsWithin 8 hours of sacrifice, 3 pig heads were cannulated via the external ophthalmic artery, perfused with PBS to remove blood, and then perfused with a fluorescent dye to label the capillaries. The posterior pole of each eye was mounted in a custom-made inflation chamber for control of IOP with simultaneous imaging. Capillaries and collagen beams were visualized with structured light illumination enhanced imaging at IOPs from 5 to 50 mm Hg at each 5 mm Hg increment. Capillary tortuosity was measured from the images and paired two-sample t-tests were used to assess for significant changes in relation to changes in IOP.ResultsCapillaries were highly tortuous at 15 mm Hg (up to 1.45). In all but one eye, tortuosity decreased significantly as IOP increased from 15 to 25 mm Hg (P < 0.01), and tortuosity decreased significantly in every eye as IOP increased from 15 to 40 mm Hg (P < 0.01). In only 16% of capillaries, tortuosity increased with elevated IOP. Capillaries had a surprisingly different topology from the collagen beams.ConclusionsAlthough high capillary tortuosity is sometimes regarded as potentially problematic because it can reduce blood flow, LC capillary tortuosity may provide slack that mitigates against reduced flow and structural damage caused by excessive stretch under elevated IOP. We speculate that low capillary tortuosity could be a risk factor for damage under high IOP.

A Layer Jamming Actuator for Tunable Stiffness and Shape-Changing Devices.

Changing the shape and the stiffness of a device in a dynamic and controlled way enables important advancements in the field of robotics and wearable robotics. Variable stiffness materials and technologies can be used to address this challenge. In particular, layer jamming actuation is a very promising technology, featured by high efficiency and low cost. In this article, a stiffness- and shape-changing device based on a novel mechanism including a multiple-chamber structure is proposed. It allows to effectively modulate the shape and stiffness of a device, by activating two jamming chambers while pressurizing/depressurizing one or more interposed inflatable chambers. Prototypes with a size of 45 × 270 mm2 and an average thickness ranging from 4.4 to 13 mm were developed and their ability to undergo a stiffness change over two orders of magnitude was demonstrated. The prototypes were also able to change their shape according to the position and inflation level of the interposed inflatable chambers, thus resulting in an overall deflection >10 mm. The possibility to wear the system as an orthotic brace was also demonstrated: this technology increased the patient comfort in static positions, yet keeping a supportive function when needed (e.g., in dynamic conditions). The device working principle highlighted in this article could also be exploited in other domains, for example, to build walking soft robots, prostheses, or grippers, as demonstrated through additional tests.

A Real-Time Thermal Model for the Analysis of Tire/Road Interaction in Motorcycle Applications

While in the automotive field the relationship between road adherence and tire temperature is mainly investigated with the aim to enhance the vehicle performance in motorsport, the motorcycle sector is highly sensitive to such theme also from less extreme applications. The small extension of the footprint, along with the need to guarantee driver stability and safety in the widest possible range of riding conditions, requires that tires work as most as possible at a temperature able to let the viscoelastic compounds-constituting the tread and the composite materials of the whole carcass structure-provide the highest interaction force with road. Moreover, both for tire manufacturing companies and for single track vehicles designers and racing teams, a deep knowledge of the thermodynamic phenomena involved at the ground level is a key factor for the development of optimal solutions and setup. This paper proposes a physical model based on the application of the Fourier thermodynamic equations to a three-dimensional domain, accounting for all the sources of heating like friction power at the road interface and the cyclic generation of heat because of rolling and to asphalt indentation, and for the cooling effects because of the air forced convection, to road conduction and to turbulences in the inflation chamber. The complex heat exchanges in the system are fully described and modeled, with particular reference to the management of contact patch position, correlated to camber angle and requiring the adoption of an innovative multi-ribbed and multi-layered tire structure. The completely physical approach induces the need of a proper parameterization of the model, whose main stages are described, both from the experimental and identification points of view, with particular reference to non-destructive procedures for thermal parameters definition. One of the most peculiar and challenging features of the model is linked with its topological and analytical structure, allowing to run in real-time, usefully for the application in co-simulation vehicle dynamics platforms, for performance prediction and setup optimization applications.

A Layered Manufacturing Approach for Soft and Soft-Rigid Hybrid Robots.

We present a manufacturing process for creating centimeter-scale multichambered inflatable robots and structures that can include both soft and rigid components. Our process uses a thermoplastic polyurethane (TPU) adhesive film to bond together layers of textiles, plastics, or other materials. The structures are heated and compressed a few layers at a time with a heat press machine or bonded in an oven all at once. We present two methods for arranging textiles and thermal adhesive film to achieve airtight structures and perform modeling and measurements on the resulting inflatable chambers. We characterize the set of textiles and rigid materials that will work with this process, measuring how strongly the TPU film bonds with them. We also describe how to include corners, where several pieces of material come together at a point, and determine which corner constructions are airtight. We characterize how different seam widths behave, determine the maximum pressure chambers fabricated with this process can support, and determine the cycle life of actuators built with this process. Finally, we present an actuator with an embedded sensor and three examples of robots constructed with textiles and TPU film, including a hybrid soft/rigid robotic arm, a soft robot that can roll along the ground, and a robot that can climb inside tubes or other confined spaces.

SOUND SUPPRESSORS FOR SMALL ARMS WITH AN ADVANCED EXPANSION CAMERA

The paper deals with information about sound suppressors for firearms when an annular expansion chamber and two-point mounting attached to the firearm barrel are used. Those patented designs are examined, as from 1910, when the patent for a sound suppressor with such chief essential features was granted. Designs of patented sound suppressors and mechanisms of their operations presented by the authors of inventions are described. The most-used designs of sound suppressors with an annular expansion chamber of the Reflex Suppressors type (Finland) are considered. The authors presented their designs of sound suppressors with an annular expansion chamber. The disadvantages of such designs are reported, including the authors’ designs. When creating mufflers (devices to reduce the sound level of the shot - PSUZV) shot sound for assault rifles (machine guns), sniper weapons, machine guns using high-energy ammunition, to obtain acceptable values for reducing the sound level of the shot muffler need to increase the volume of the hollow volume . This leads to problems in the operation of the weapon with the silencer and ensure the consistency of the barrel of the weapon and the silencer with a single point attachment to the cut of the barrel. One way to solve this problem is to create a muffler with an optional expansion chamber that covers the outside of the barrel and is gas-dynamically coupled to a traditional expansion chamber that protrudes beyond the barrel section through a permeable partition. The main structural elements of such a muffler - inflatable and overhead expansion chambers, a permeable partition between them and two points of attachment - in the cut of the trunk and, as a rule, at the end of the overhead expansion chamber. Information sources, in which data about the special features of thermogasdynamic processes in sound suppressors were published, are listed. In accordance with the results of their analyses variations needed for the sound suppressor design are validated to improve its characteristics. The sound suppressor design, in which outlined variations were realized, is described and the results of fullscale tests are presented. The conclusion about rationality of using the authors’sound suppressors is made, in particular for highpower ammunition of firearms.

Design, Modeling, and Testing of a Soft Pneumatic Glove With Segmented PneuNets Bending Actuators

This paper presents the design, modeling, and testing of a soft pneumatic glove with five segmented PneuNets bending actuators (SPBAs) made of elastomer, each actuator driving the corresponding finger to bend. The segmented structure of the actuator is designed according to the anatomy of human fingers, i.e., three flexible segments for finger joints and four inflexible segments for finger metacarpal and phalanges, which makes the actuator fit with finger better than those of homogenous structure. The number of inflatable chambers in the flexible segment can be designed according to range of motion (ROM) of the corresponding joint. To improve the air tightness of the actuator, an inner bladder is embedded into chambers. To predict the passive bending degree and grasping force of human fingers driven by the glove, a bottom–up model is constructed by using Yeoh's theory of hyperelasticity and Lagrange equations of serial robots. The model is verified by FEM simulations and experiments simultaneously. At last, some passive exercises are presented, which indicates its potential in hand rehabilitation.

TRT EVO: Advances in real-time thermodynamic tire modeling for vehicle dynamics simulations

Vehicle performances, especially in motorsport, are deeply affected by tire behavior and in particular by tire compound proper working conditions. In this research activity, a series of innovations have been introduced on the Thermo Racing Tire (a physical-analytical tire thermal model, based on Fourier’s law of heat transfer applied to a three-dimensional domain) in order to take into account all the main aspects actively involved in the thermal behavior of the tire, as the presence of exhausted gases eventually impacting at the rear axle and the inhomogeneous distribution of local variables (pressure, stress and sliding velocity) within the contact patch, caused in example by the tire camber angle. The new model developed considers the presence of the sidewalls, actively involved in the convective heat exchanges, respectively, with the external airflow and the inner gas fluid, located inside the inflation chamber. The aim of the new version of the tire thermal model is a better physical comprehension of all the phenomena concerning the contact with the asphalt and the prediction of the link between the thermal state and the frictional performance, crucial for the definition of an optimal wheel and vehicle setup.

A Novel Fabric-Based Versatile and Stiffness-Tunable Soft Gripper Integrating Soft Pneumatic Fingers and Wrist.

This work presents the design and test of a novel fabric-based versatile and stiffness-tunable soft gripper integrating soft pneumatic fingers and wrist. The morphology is designed into a compact tuning fork shape (130 × 110 × 260 mm, 389 g) with two bidirectional sheet-shaped soft fingers and a biaxial bidirectional (universal) cylinder-shaped soft wrist. The multi-degree of freedom of soft fingers and wrist makes the gripper versatile and adaptable to gripping objects of various shapes, sizes, and orientations in a wide range. The bidirectional fingers with double-side inflatable chambers can tune their gripping stiffness and force by varying the common and differential pressure of the two sides. The wrist can tune its deflecting stiffness and force in the same way. Therefore, the gripper can grip objects of various stiffness and weights. The soft gripper is tested to characterize its workspace, stiffness, gripping force, and dynamic response time. Gripping function tests are also performed to evaluate the achieved degree of functions of the gripper. Tests show that the proposed gripper can grip objects in the size of 0-245 mm and in the orientation of -88.2°-90.8° (pitch/roll) with a maximum gripping force of 40 N and a response time of 1.22-1.60 s to force and 0.56-2.61 s to motion, respectively. The gripping stiffness can be tuned in the range of 0.029-0.137 N/mm (i.e., the tunable scope is 79%) by varying common pressure in the range of 0-0.2 MPa. Functional tests verify that the proposed soft gripper is versatile and adaptable to gripping objects of various shapes, sizes, weights, and orientations. Therefore, the proposed soft gripper has great potential applications in production and daily life.

Esophageal Peristaltic Control of a Soft-Bodied Swallowing Robot by the Central Pattern Generator

Dysphagia, the medical term for swallowing disorders, is a major problem for the elderly, leading to low quality of life, high cost of care, and at times, to death. One approach to improving the safety and efficiency of the swallowing process in dysphagic patients is to provide foods with modified viscosities. In this study, a bioinspired swallowing robot with an embedded stretchable deformation sensor matrix has been developed as an in vitro simulator to simulate the human swallowing process, with the control of a central pattern generator (CPG) model to generate peristaltic wave signals. The robot is soft bodied and pneumatically actuated, constructed from silicon rubber with layers of inflatable chambers. The CPG generated oscillations are taken as electrical signals to prescribe the pressure in the inflatable chambers. The prescribed pressure is regulated through proportional valves. The CPG is designed according to the principle of harmonic balance, and the design procedure is implemented in a graphical user interface. Based on the experimental data, a lookup table is developed to relate the input voltages for the pressure in the chambers to the robot's conduit surface deformation. A nanocomposite-based stretchable deformation sensor matrix is embedded into the swallowing robot to determine the deformation based on changes in resistance. Pressure trajectories are generated by the CPG for a desired peristaltic waveform. Three sensing pads are used to determine the conduit deformation. Conduit deformation is converted from sensors resistance changes and the results show that the CPG is able to produce the oscillatory signals needed to achieve the peristaltic wave movement in the soft-bodied swallowing robot.

The pressure-induced deformation response of the human lamina cribrosa: Analysis of regional variations.

Glaucoma causes vision loss through progressive damage of the retinal ganglion axons at the lamina cribrosa (LC), the connective tissue structure that supports the axons as they leave the eye. Mechanical characterization of the LC is challenging because of the complex 3D shape and inaccessibility of the tissue. We present a new method using digital volume correlation to map the 3D displacement and strain fields in the LC under inflation. We report for the first time significant regional variations in the strains that are consistent with the pattern of optic nerve damage in early glaucoma. Thus regional strain variations may be predictive of the progression of axonal damage in glaucoma.

Soft Actuator Mimicking Human Esophageal Peristalsis for a Swallowing Robot

Provision of modified foods and drinks is one of the approaches for dysphagia management, which is based on the assumption that food with proper texture and rheological properties will allow dysphagia patients to swallow safely and maintain adequate nutrition. However, lack of information about the in vivo swallowing process and its interaction with food flow has obstructed the effective management of dysphagia. In the esophageal swallowing stage, masticated food is transported through the esophagus to the stomach by a peristaltic mechanism, which is generated by sequential contraction and relaxation of esophageal muscles. Inspired by this behavior, a soft actuator is proposed to provide a nonrisk environment aiming to facilitate investigations of the most effective properties of food for the management of the swallowing disorders. The wave-like motion is first specified according to the in vivo measurement of human esophageal peristalsis. Finite-element analysis simulations are carried out to aid the structure design before prototype manufacture. Constructed by casting silicon rubber in a three-dimensional (3-D) printed customized mold, the novel actuator has soft structure resembling its human counterpart, which has a flexible muscular structure. Multiple layers of inflatable chambers are embedded and distributed along the axis of a food passage regularly, which locates at the center of the actuator. The actuator is capable of generating a peristaltic wave and pushing a bolus along the passage. The closure of the tube and the velocity of the propagation wave are going to be adjusted to achieve the trajectories recorded experimentally, by regulating the compressed air pressure pumped into chambers actively.

Biomechanics of the Human Posterior Sclera: Age- and Glaucoma-Related Changes Measured Using Inflation Testing

The objective of this study was to measure the biomechanical response of the human posterior sclera in vitro and to estimate the effects of age and glaucoma. Scleral specimens from 22 donors with no history of glaucoma and 11 donors with a history of glaucoma were excised 3 mm posterior to the equator and affixed to an inflation chamber. Optic nerve cross-sections were graded to determine the presence of axon loss. The time-dependent inflation response was measured in a series of pressure-controlled load-unload tests to 30 mm Hg and creep tests to 15 and 30 mm Hg. Circumferential and meridional strains were computed from the digital image correlation displacements, and midposterior stresses were determined from pressure and deformed geometry. Among normal specimens, older age was predictive of a stiffer response and a thinner sclera. In the age group 75 to 93, diagnosed glaucoma eyes with axon damage were thicker than normal eyes. Both damaged and undamaged glaucoma eyes had a different strain response in the peripapillary sclera characterized by a stiffer meridional response. Undamaged glaucoma eyes had slower circumferential creep rates in the peripapillary sclera than normal eyes. Glaucoma eyes were not different from normal eyes in stresses and strains in the midposterior sclera. The observed differences in the biomechanical response of normal and glaucoma sclera may represent baseline properties that contribute to axon damage, or may be characteristics that result from glaucomatous disease.

A Methane Balloon Inflation Chamber

While several lecture demonstrations are possible using methane-filled balloons, it is often inconvenient to prepare these balloons since the pressure from standard laboratory and lecture hall gas nozzles is too low. As a solution to this problem, a methane balloon inflation chamber, prepared from a translucent 3.5-gallon pail and an aspirator or house-vacuum, provides an inexpensive and convenient method for inflating balloons in laboratories or lecture halls. Prepared in this way, methane-filled balloons can be used to demonstrate the effects of vacuum, the lifting power of low-density gases, and the explosive combustion of methane.Find this demonstration and others in the DigiDemos area of the JCE Digital Library.