Contact-Resistance-Free Stretchable Strain Sensors with High Repeatability and Linearity

Abstract

Most of the existing stretchable strain sensors are based on the contact-resistance mechanism, where the stretchability and resistance variation depend on the change of the contact relationship of the conductive microstructures. These sensors usually exhibit large sensing ranges and gauge factors but unsatisfactory repeatability and linearity of the electrical responses because the contact is unstable. Here, we report a completely different design for stretchable strain sensors based on a contact-resistancefree structure, i.e., the off-axis serpentine sandwich structure (OASSS), with the mechanism of the stretch−bending−stretch transformation (SBST). Neither unstable contact resistance nor nonlinear constitutive and geometric behaviors occur for the OASSS while the sensor undergoes a large applied strain (50%), which guarantees high repeatability (repeatability error = 1.58%) and linearity (goodness-of-fit >0.999). Owing to such performances, the present sensors are not only applied to monitoring human activities and medical surgery but also to the ground tests of Tianwen-1, China's first Mars exploration mission.

Skin bioelectronics towards long-term, continuous health monitoring

“…To achieve stretchability with rigid materials, appropriate geometry design can be utilised to obtain stretchable structures, such as net-shaped, island-bridge, kirigami, serpentine, and in-/out-of plane buckles. 235,236 Also, many researchers have developed high-performance mechanical flexibility/ stretchability with combined strategies. 88 For example, Wang et al developed a highly stretchable transparent electrode combining soft vertically aligned AuNWs and porous stretchable nanomesh structures.…”

Topological Gradients for Metal Film-Based Strain Sensors

“…Stretchable strain sensors (SSSs) have attracted great attention nowadays due to the extensive applications in soft robotics, human-machine interaction, health-monitoring systems, and human motion detection. − Conventional metal foils-based strain sensors have low sensitivity (∼2) and narrow sensing range (<5%), , which failed to monitor the full-range human activities, such as subtle physiological signals (<1%) and vigorous joint movements (>50%). − Bioinspired by the crack-shaped slit sensory organs of a spider, Choi’s group first proposed an ultrasensitive crack-based strain sensor by depositing a Pt layer on a polyurethane acrylate (PUA) layer. The disconnection–reconnection process of the nanoscale cracks under minute deformation induces a huge change in the electrical resistance of metal films, leading to an ultrahigh mechanosensitivity with a gauge factor (GF ∼ 2000) in the 0–2% strain range.…”

Hybrid patterning of metal nanowire/polymer composites based on selective photocuring-and-transfer and kirigami cutting techniques for stretchable circuit application

“…Importantly, the long-term stability at high strain (1000 cycles at 100% strain) will allow the kirigami composite conductors to reliably work in various stretchable and skin-mountable electronic systems that are usually exposed to large-scale human activities inducing strains of 50% or more. 40,41…”

“…Importantly, the long-term stability at high strain (1000 cycles at 100% strain) will allow the kirigami composite conductors to reliably work in various stretchable and skin-mountable electronic systems that are usually exposed to large-scale human activities inducing strains of 50% or more. 40,41 Based on the excellent electrical properties and stretchability of the kirigami AgNW/UCP composite conductor, the device could be successfully used as a wearable heater. Fig.…”