Inverse design of artificial skins

Mimicking the perceptual functions of human cutaneous mechanoreceptors, artificial skins or flexible pressure sensors can transduce tactile stimuli to quantitative electrical signals. Conventional methods to design such devices follow a forward structure-to-property routine based on trial-and-error experiments/simulations, which take months or longer to determine one solution valid for one specific material. Target-oriented inverse design that shows far higher output efficiency has proven effective in other fields, but is still absent for artificial skins because of the difficulties in acquiring big data. Here, we report a property-to-structure inverse design of artificial skins based on small dataset machine learning, exhibiting a comprehensive efficiency at least four orders of magnitude higher than the conventional routine. The inverse routine can predict hundreds of solutions that overcome the intrinsic signal saturation problem for linear response in hours, and the solutions are valid to a variety of materials. Our results demonstrate that the inverse design allowed by small dataset is an efficient and powerful tool to target multifarious applications of artificial skins, which can potentially advance the fields of intelligent robots, advanced healthcare, and human-machine interfaces

Minsight: A Fingertip-Sized Vision-Based Tactile Sensor for Robotic Manipulation

Intelligent interaction with the physical world requires perceptual abilities beyond vision and hearing; vibrant tactile sensing is essential for autonomous robots to dexterously manipulate unfamiliar objects or safely contact humans. Therefore, robotic manipulators need high-resolution touch sensors that are compact, robust, inexpensive, and efficient. The soft vision-based haptic sensor presented herein is a miniaturized and optimized version of the previously published sensor Insight. Minsight has the size and shape of a human fingertip and uses machine learning methods to output high-resolution maps of 3D contact force vectors at 60 Hz. Experiments confirm its excellent sensing performance, with a mean absolute force error of 0.07 N and contact location error of 0.6 mm across its surface area. Minsight's utility is shown in two robotic tasks on a 3-DoF manipulator. First, closed-loop force control enables the robot to track the movements of a human finger based only on tactile data. Second, the informative value of the sensor output is shown by detecting whether a hard lump is embedded within a soft elastomer with an accuracy of 98%. These findings indicate that Minsight can give robots the detailed fingertip touch sensing needed for dexterous manipulation and physical human-robot interaction

A spiking and adapting tactile sensor for neuromorphic applications

The ongoing research on and development of increasingly intelligent artificial systems propels the need for bio inspired pressure sensitive spiking circuits. Here we present an adapting and spiking tactile sensor, based on a neuronal model and a piezoelectric field-effect transistor (PiezoFET). The piezoelectric sensor device consists of a metal-oxide semiconductor field-effect transistor comprising a piezoelectric aluminium-scandium-nitride (AlxSc1-xN) layer inside of the gate stack. The so augmented device is sensitive to mechanical stress. In combination with an analogue circuit, this sensor unit is capable of encoding the mechanical quantity into a series of spikes with an ongoing adaptation of the output frequency. This allows for a broad application in the context of robotic and neuromorphic systems, since it enables said systems to receive information from the surrounding environment and provide encoded spike trains for neuromorphic hardware. We present numerical and experimental results on this spiking and adapting tactile sensor

Miniaturized Piezo Force Sensor for a Medical Catheter and Implantable Device

Real-time monitoring of intrabody pressures can benefit from the use of miniaturized force sensors during surgical interventions or for the recovery period thereafter. Herein, we present a force sensor made of poly(vinylidene fluoride)-co-trifluoroethylene (P(VDF-TrFE)) with a simple fabrication process that has been integrated into the tip of a medical catheter for intraluminal pressure monitoring, as well as into an implantable device with a power consumption of 180 μW obtained by the near-field communication (NFC) interface to monitor the arterial pulse at the subcutaneous level (≤1 cm). The pressure range supported by the sensor is below 40 kPa, with a signal responsivity of 0.63 μV/Pa and a mean lifetime expectancy of 400 000 loading cycles inside physiological conditions (12 kPa). The proposed sensor has been tested experimentally with synthetic anatomical models for the lungs (bronchoscopy) and subcutaneous tissue, as well as directly above the human carotid and radial arteries. Information about these pressure levels can provide insights about tissue homeostasis inside the body as fluid dynamics are altered in some health conditions affecting the hemodynamic and endocrine body systems, whereas for surgical interventions, precise control and estimation of the pressure exerted by a catheter over the internal walls are necessary to avoid endothelium injuries that lead to bleeding, liquid extravasation, or flow alteration associated with atheroma formation

Functional mimicry of Ruffini receptors with fibre Bragg gratings and deep neural networks enables a bio-inspired large-area tactile-sensitive skin

Collaborative robots are expected to physically interact with humans in daily living and the workplace, including industrial and healthcare settings. A key related enabling technology is tactile sensing, which currently requires addressing the outstanding scientific challenge to simultaneously detect contact location and intensity by means of soft conformable artificial skins adapting over large areas to the complex curved geometries of robot embodiments. In this work, the development of a large-area sensitive soft skin with a curved geometry is presented, allowing for robot total-body coverage through modular patches. The biomimetic skin consists of a soft polymeric matrix, resembling a human forearm, embedded with photonic fibre Bragg grating transducers, which partially mimics Ruffini mechanoreceptor functionality with diffuse, overlapping receptive fields. A convolutional neural network deep learning algorithm and a multigrid neuron integration process were implemented to decode the fibre Bragg grating sensor outputs for inference of contact force magnitude and localization through the skin surface. Results of 35 mN (interquartile range 56 mN) and 3.2 mm (interquartile range 2.3 mm) median errors were achieved for force and localization predictions, respectively. Demonstrations with an anthropomorphic arm pave the way towards artificial intelligence based integrated skins enabling safe human–robot cooperation via machine intelligence

Multifunctional electronic skin with a stack of temperature and pressure sensor arrays

This paper presents multifunctional electronic skin (e-Skin) with a stack of pressure and temperature sensors arrays. The pressure sensor layer comprises of an 8x 8 array of capacitive sensors using soft elastomers as the dielectric medium and the temperature sensing layer comprises of 4 x4 array of conductive polymers based resistive sensors. Three variants of capacitive pressure sensors were developed using two different dielectric materials (PDMS and Ecoflex) to find the best combination of performance and softness. The Ecoflex-based pressure sensor showed high sensitivity (~4.11 kPa-1) at a low-pressure regime (<1 kPa) and the 7.5:1 PDMS based pressure sensor showed high sensitivity (~2.32 kPa-1) in the high-pressure regime (>1 kPa). Two variants of temperature sensors were fabricated using CNT and CNT & PEDOT:PSS conducting polymer composite and their performance compared. Finally, a highly sensitive CNT+PEDOT:PSS based resistive temperature sensors layer was integrated on top of 7.5:1 PDMS based capacitive pressure sensors layer to realize the e-Skin prototype. The developed e-Skin is capable of sensing pressures greater than 10 kPa with a high sensitivity of ~2.32 kPa-1 at 1 kPa and temperatures with the sensitivity of ~ 0.64 (%)/(°C) up to 80°C, thus demonstrating high potential for use in robotics and touch based interactive systems

Soft Robotics: An Exploration of Inspired Technologies by Biological Organisms for Medical Applications.

La robótica blanda y en especial la robótica blanda bioinspirada es un campo que tiene una gran capacidad para aplicaciones médicas, debido a que se centra en el desarrollo de dispositivos más amigables con el ser humano y que se adapten más a entornos biológicos. Para la búsqueda de la información que se trata en el presente artículo se realizó la búsqueda de las palabras clave en bases de datos que contenían material científico y de resultados de investigación, y se extrajo alguna de la información más relevante de acuerdo con diferentes criterios de inclusión. El principal resultado de este artículo es la exploración de tecnologías robóticas bioinspiradas y usadas en robótica blanda las cuales pudieran usarse en el desarrollo de dispositivos, procesos o procedimientos médicos. Con la información encontrada se logró dar un vistazo general de las principales tecnologías robóticas bioinspiradas, las que se usan en el desarrollo de robots blandos y como pudieran llegar a integrarse y complementarse para la solución de problemas en el campo de la medicina y la bioingeniería.Soft robotics and especially bio inspired soft robotics is a field that has a great capacity for medical applications, because it focuses on the development of devices that are more human-friendly and that adapt to more biological environments. For the search of the information that is dealt with in this article, the search of the key words was carried out in databases that contained scientific material and research results, and some of the most relevant information was extracted according to different criteria. The main result of this article is the exploration of bio inspired robotic technologies used in soft robotics which could be used in the development of medical devices, processes or procedures. With the information found, it was possible to give an overview of the main bio inspired robotic technologies, those used in the development of soft robots and how they could be integrated and complemented for the solution of problems in the field of medicine and bioengineering

Air/water interfacial assembled rubbery semiconducting nanofilm for fully rubbery integrated electronics

A rubber-like stretchable semiconductor with high carrier mobility is the most important yet challenging material for constructing rubbery electronics and circuits with mechanical softness and stretchability at both microscopic (material) and macroscopic (structural) levels for many emerging applications. However, the development of such a rubbery semiconductor is still nascent. Here, we report the scalable manufacturing of high-performance stretchable semiconducting nanofilms and the development of fully rubbery transistors, integrated electronics, and functional devices. The rubbery semiconductor is assembled into a freestanding binary-phased composite nanofilm based on the air/water interfacial assembly method. Fully rubbery transistors and integrated electronics, including logic gates and an active matrix, were developed, and their electrical performances were retained even when stretched by 50%. An elastic smart skin for multiplexed spatiotemporal mapping of physical pressing and a medical robotic hand equipped with rubbery multifunctional electronic skin was developed to show the applications of fully rubbery-integrated functional devices