Stretchable elastic synaptic transistors for neurologically integrated soft engineering systems

Artificial synaptic devices that can be stretched similar to those appearing in soft-bodied animals, such as earthworms, could be seamlessly integrated onto soft machines toward enabled neurological functions. Here, we report a stretchable synaptic transistor fully based on elastomeric electronic materials, which exhibits a full set of synaptic characteristics. These characteristics retained even the rubbery synapse that is stretched by 50%. By implementing stretchable synaptic transistor with mechanoreceptor in an array format, we developed a deformable sensory skin, where the mechanoreceptors interface the external stimulations and generate presynaptic pulses and then the synaptic transistors render postsynaptic potentials. Furthermore, we demonstrated a soft adaptive neurorobot that is able to perform adaptive locomotion based on robotic memory in a programmable manner upon physically tapping the skin. Our rubbery synaptic transistor and neurologically integrated devices pave the way toward enabled neurological functions in soft machines and other applications

Flexible Micro-Nano Fiber Sensors for Tactile Sensing

Flexible tactile sensors play an important role in wearable devices, human–computer interaction devices, and advanced robotics. We propose a novel structure of bionic flexible tactile sensor. The micro-nano fibers (MNFs) are packed in a 10-μm film on a polydimethylsiloxane (PDMS) base, forming a thin film-MNF-PDMS structure. A ridge-shaped sensing region is formed on the surface of the PDMS substrate. The MNF is so close to the sensor surface that vibration and pressure signals can act directly on the MNF. Compared to existing MNF flexible sensors, this sensor has higher sensitivity and faster response time. We tested the response of the flexible sensor to vibration and temperature. This sensor can measure vibration signals from 0.1 Hz to2 kHz. The sensitivity of this sensor to temperature can reach 1.43 nm/◦C. Surfaces with different roughness or texture can be distinguished by sliding on the sensor surface. The structural and functional characteristics of this sensor are desirable in flexible bionic devices and advanced robots

A Flexible Piezoresistive/Self-Capacitive Hybrid Force and Proximity Sensor to Interface Collaborative Robots

Force and proximity sensors are key in robotics, especially when applied in collaborative robots that interact physically or cognitively with humans in real unstructured environments. However, most existing sensors for use in robotics are limited by: 1) their scope, measuring single parameters/events and often requiring multiple types of sensors, 2) being expensive to manufacture, limiting their use to where they are strictly necessary and often compromising redundancy, and 3) have null or reduced physical flexibility, requiring further costs with adaptation to a variety of robot structures. This paper presents a novel mechanically flexible force and proximity hybrid sensor based on piezoresistive and self-capacitive phenomena. The sensor is inexpensive and easy to apply even on complex-shaped robot structures. The manufacturing process is described, including controlling circuits, mechanical design, and data acquisition. Experimental trials featuring the characterisation of the sensor were conducted, focusing on both force-electrical resistance and self-capacitive proximity response. The sensor's versatility, flexibility, thinness (1 mm thickness), accuracy (reduced drift) and repeatability demonstrated its applicability in several domains. Finally, the sensor was successfully applied in two distinct situations: hand guiding a robot (by touch commands), and human-robot collision avoidance (by proximity detection)

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