Self‐Shaping Soft Electronics Based on Patterned Hydrogel with Stencil‐Printed Liquid Metal

Abstract

Hydrogel-based soft electronics (HSE) is promising as implantable devices due to the similarity of hydrogel substrates to biologic tissues. Most existing HSE devices are based on conducting hydrogels that usually have weak mechanical properties, low conductivity, and poor patternability. Reported here is an HSE with good mechanical performance, high sensitivity, and versatile functions by stencil printing of liquid metal on a tough hydrogel, facilitating integration of multiple sensing units. Self-shaping ability is imparted to the HSE by creating gradient structure in the hydrogel substrate. The resultant HSE actively deforms into 3D configurations with zero or nonzero Gaussian curvature to fix on objects or organs with sophisticated geometries and maintains the sensing functions. The versatilities and potential applications of this HSE are demonstrated by monitoring motions of a rice field eel and beatings of a rabbit heart. Such HSE based on morphing substrate should pave the way for implantable electronics with better fixation and interfacial contact with the organs. The concept of morphing hydrogel devices can be extended to other soft electronics with responsive polymer films or elastomers as the substrates.

Liquid Metal Patterned Stretchable and Soft Capacitive Sensor with Enhanced Dielectric Property Enabled by Graphite Nanofiber Fillers

“…This breaking and reformatting the oxide layer continues till the viscosity of the material is enough to resist rotation of the stirrer ensuing formation of highly oxidized EGaIn [86] with bulk resistivity ~1.21 times that of pure EGaIn (Figure S3). This highly oxidized and viscous material could easily be deposited as electrode on the composite's surface by stencil printing, which is a kind of forced wetting method [81,87,88]. Prior to electrode printing, the contact angles made by water and EGaIn on the composite (PGNC@6wt %) were compared to that of pure PDMS and no significant difference was observed (Figure 7a-d) which indicated negligible changes in surface wetting behaviors by the GNF fillers.…”

Highly Stretchable Hydrogels as Wearable and Implantable Sensors for Recording Physiological and Brain Neural Signals

“…The mechanical performances of HM-2 and other recently reported wearable or implantable hydrogels have been shown in Figure S3 in the Supporting Information. [48][49][50][51][52][53][54][55] It can be seen that the microgels exhibit different influences on mechanical performance in comparison to traditional rigid nanofillers such as carbon nanotubes, MXene, cellulose nanocrystals, etc. The microgels lead to a larger stretchability and retain a relatively lower elastic modulus in comparison to traditional rigid nanofillers.…”

Multi‐Network Poly(β‐cyclodextrin)/PVA/Gelatin/Carbon Nanotubes Composite Hydrogels Constructed by Multiple Dynamic Crosslinking as Flexible Electronic Devices

“…Fan et al [88] designed an antibacterial dual network hydrogel-based strain sensor used to detect the rat liver motion. Wu and co-workers [89] developed a kind of self-shaping hydrogel-based soft electronics for the monitoring of rabbit heart movement. Here, the present strain sensor was further employed to monitor the motion of a dynamic organ.…”