Shielded soft force sensors

Abstract

Force and strain sensors made of soft materials enable robots to interact intelligently with their surroundings. Capacitive sensing is widely adopted thanks to its low power consumption, fast response, and facile fabrication. Capacitive sensors are, however, susceptible to electromagnetic interference and proximity effects and thus require electrical shielding. Shielding has not been previously implemented in soft capacitive sensors due to the parasitic capacitance between the shield and sensing electrodes, which changes when the sensor is deformed. We address this crucial challenge by patterning the central sensing elastomer layer to control its compressibility. One design uses an ultrasoft silicone foam, and the other includes microchannels filled with liquid metal and air. The force resolution is sub-mN both in normal and shear directions, yet the sensor withstands large forces (>20 N), demonstrating a wide dynamic range. Performance is unaffected by nearby high DC and AC electric fields and even electric sparks.

An optical-based multipoint 3-axis pressure sensor with a flexible thin-film form

“…Meanwhile, recognition of multipoint pressure distribution by sensor array allows us to obtain a complete pressure interaction profile (3)(4)(5), and complemented by artificial intelligence and data analytics, researchers already show the feasibility of more intelligent sensing functions such as grasping recognition (6)(7)(8) and slip detection (2,9). In addition, the thin and lightweight sensor form is also essential, as this contributes to the feasibility and flexibility of system-level integration (10)(11)(12). The advances in the function and shape of tactile pressure sensors will further lead to unprecedented breakthroughs in robotics (13)(14)(15), medical or welfare devices (16)(17)(18), as well as human-computer interaction systems (19,20).…”

“…To realize both normal and tangential stress response like human tactile receptors, many research groups have designed capacitive or resistive-based sensors with sophisticated structure engineering (11)(12)(13)(21)(22)(23). A typical structure is to use an array of capacitors or resistors with different response modes to normal and tangential pressure as a 3-axis pressure sensing unit.…”

High Anti‐Jamming Flexible Capacitive Pressure Sensors Based on Core–Shell Structured AgNWs@TiO2

“…Therefore, electromagnetic shielding measures, generally consisting of metallic meshes or screens, must be taken, which brings inconvenience to the design and use of capacitive sensors. [28,29] On the other hand, the parasitic capacitance will be increased between the shield and sensing electrodes due to shielding measures. Compared with the constant parasitic capacitance of traditional rigid devices, it will be changed with the deformation of flexible devices due to the corresponding change in the distance between the shield and the sensing electrode under pressure.…”

All Knitted and Integrated Soft Wearable of High Stretchability and Sensitivity for Continuous Monitoring of Human Joint Motion

“…[ 49 ] Although capacitive sensors allow for easier calibration due to their nearly linear response, a major drawback of capacitive sensors is they are prone to electromagnetic interference from the external environment, for example, proximity to the human body, and therefore typically require shielding. [ 49,50 ]…”

“…[49] Although capacitive sensors allow for easier calibration due to their nearly linear response, a major drawback of capacitive sensors is they are prone to electromagnetic interference from the external environment, for example, proximity to the human body, and therefore typically require shielding. [49,50] In this work, we developed highly stretchable conductive textiles through the mechanical coupling of an electrically conductive yarn (Young's modulus, E c 1535 MPa) and a dielectric yarn of high elasticity (Young's modulus ratio, E c / E d > 10 3 ) in various stitch patterns. The highly elastic dielectric yarn (maximum strain: ≈448%) stretches significantly compared to the conductive yarn (maximum strain: <1.5%) while also controlling the electrical contact points of the conductive yarn in the following manners: 1) the periodic formation and breaking of contact points in a resistive strain sensor; 2) preserving original contact points in an interconnect; or 3) preventing formation of contact points in a resistor.…”