Nanoengineered Ink for Designing 3D Printable Flexible Bioelectronics

Abstract

Flexible electronics require elastomeric and conductive biointerfaces with native tissue-like mechanical properties. The conventional approaches to engineer such a biointerface often utilize conductive nanomaterials in combination with polymeric hydrogels that are cross-linked using toxic photoinitiators. Moreover, these systems frequently demonstrate poor biocompatibility and face trade-offs between conductivity and mechanical stiffness under physiological conditions. To address these challenges, we developed a class of shear-thinning hydrogels as biomaterial inks for 3D printing flexible bioelectronics. These hydrogels are engineered through a facile vacancy-driven gelation of MoS2 nanoassemblies with naturally derived polymer-thiolated gelatin. Due to shear-thinning properties, these nanoengineered hydrogels can be printed into complex shapes that can respond to mechanical deformation. The chemically cross-linked nanoengineered hydrogels demonstrate a 20-fold rise in compressive moduli and can withstand up to 80% strain without permanent deformation, meeting human anatomical flexibility. The nanoengineered network exhibits high conductivity, compressive modulus, pseudocapacitance, and biocompatibility. The 3D-printed cross-linked structure demonstrates excellent strain sensitivity and can be used as wearable electronics to detect various motion dynamics. Overall, the results suggest that these nanoengineered hydrogels offer improved mechanical, electronic, and biological characteristics for various emerging biomedical applications including 3D-printed flexible biosensors, actuators, optoelectronics, and therapeutic delivery devices.

N, S Co-Coordinated Mo Defect Sites in Metal Coordination Polymers for Boosting Perdurable and High-Efficiency Alkaline Hydrogen Evolution

“…Notably, a broad peak centered at 317 cm –1 assigned to δ(MoO) and υ(Mo–S) appeared in the electrolyte and became rather narrow and sharp with the potential decrease from −1.07 to −1.21 V vs Ag/AgCl for Mo-NT@NF; this indicated the enhanced orderliness on the Mo–(S/O) site during the H 2 evolution process. , The emergence of the peak at around 154 cm –1 could be assigned to the vibration modes of Mo–N . Intriguingly, the broad peak located at 1635 cm –1 [υ(−OH)] emerged and enhanced with the further decrease of the applied potentials, accompanying the emergence of a sharp peak at 2330 cm –1 [(υ(S–H)], 317 cm –1 [δ(MoO) and υ(Mo–S)] and 154 cm –1 υ(Mo–N), reflecting that S–Mo(O)–N in Mo–NT@NF takes part in the alkaline HER process. , …”

“…47 Intriguingly, the broad peak located at 1635 cm −1 [υ(−OH)] emerged and enhanced with the further decrease of the applied potentials, accompanying the emergence of a sharp peak at 2330 cm −1 [(υ(S−H)], 317 cm −1 [δ(Mo�O) and υ(Mo−S)] and 154 cm −1 υ(Mo−N), reflecting that S−Mo(�O)−N in Mo−NT@NF takes part in the alkaline HER process. 48,49 To better understand the origin of the catalytic activity of Mo−NT@NF, we investigated changes in the structural and chemical compositions of Mo−NT@NF materials after stability tests through ex situ XPS and Raman spectra studies. The doublets attributed to Mo 6+ and Mo 5+ 3d located at 232.1/235.3 and 230.4/233.6 eV negatively shifted after the stability test, indicating the increased electron density at Mo sites 50 (Figure 2a).…”

Emerging biotransduction strategies on soft interfaces for biosensing

“…wave, wrinkle, island-bridge, origami, textile, and crack), which allows for conformability, high electron/hole mobility, low impedance/resistance, high throughput, and satisfactory sensing performance. [24][25][26][27][28] For biomolecule detection, as biomolecules could not directly produce detectable signals, biosensors generally need an extra biotransducer to selectively recognize molecules and subsequently produce electrical or optical signals. Hence, it is necessary to summarize efficient biotransduction strategies for better soft biosensors.…”

Additive Manufacturing of Stretchable Polyurethane/Graphene/Multiwalled Carbon Nanotube-Based Conducting Polymers for Strain Sensing

“…However, DIW and FDM lack the precision of microflow control systems, compromising the accuracy and speed of formation. ,, The optical curing technology through digital chip control, such as digital light processing (DLP) optical curing technology, enables curing layer-by-layer by forming a resin between layers, facilitating high-speed complex compositions. , Currently available curing and forming methods produce weak/less stretching sensors . A flexible strain sensor requires reliable mechanical strength and sensing performance. , The human skin-like stretching strain of 25%, the amount of Young’s module of human skin is 25–220 kPa. , The elastic materials, polyurethane, hydrogel, , silicon, , etc., are commonly used for curing. Among them, polyurethane exhibits high performance due to the hydrogen bonds between polyurethane chains .…”