Ultrastretchable, Self-Healing Conductive Hydrogel-Based Triboelectric Nanogenerators for Human–Computer Interaction

Abstract

The rapid development of wearable electronic devices and virtual reality technology has revived interest in flexible sensing and control devices. Here, we report an ionic hydrogel (PTSM) prepared from polypropylene amine (PAM), tannic acid (TA), sodium alginate (SA), and MXene. Based on the multiple weak H-bonds, this hydrogel exhibits excellent stretchability (strain >4600%), adhesion, and self-healing. The introduction of MXene nanosheets endows the hydrogel sensor with a high gauge factor (GF) of 6.6. Meanwhile, it also enables triboelectric nanogenerators (PTSM-TENGs) fabricated from silicone rubber-encapsulated hydrogels to have excellent energy harvesting efficiency, with an instantaneous output power density of 54.24 mW/m 2 . We build a glove-based human−computer interaction (HMI) system using PTSM-TENGs. The multidimensional signal features of PTSM-TENG are extracted and analyzed by the HMI system, and the functions of gesture visualization and robot hand control are realized. In addition, triboelectric signals can be used for object recognition with the help of machine learning techniques. The glove based on PTSM-TENG achieves the classification and recognition of five objects through contact, with an accuracy rate of 98.7%. Therefore, strain sensors and triboelectric nanogenerators based on hydrogels have broad application prospects in man−machine interface, intelligent recognition systems, auxiliary control systems, and other fields due to their excellent stretchable and high self-healing performance.

Ultrastretchable High-Conductivity MXene-Based Organohydrogels for Human Health Monitoring and Machine-Learning-Assisted Recognition

“…and negatively charged hydrophilic surfaces of MXene nanosheets, their excellent water dispersion and strong interactions (hydrogen bond and electrostatic interactions) with polymeric networks endow the related hydrogel with excellent mechanical stretchability. 29 In addition, the unique metallic conductivity of MXene nanosheets and large specific surface area will form continuously conductive pathways in hydrogels to render a high conductivity of the MXene-based hydrogels. Meanwhile, under strain or pressure the sliding and stacking of MXene nanosheets in the hydrogel matrix distinctly alter the number and length of conductive paths to result in their resistance variation, which would endow promising prospects of the MXene-based hydrogels as piezoresistive sensing devices.…”

“…Benefiting from the abundant surface functional groups (−O, −OH, −F, etc.) and negatively charged hydrophilic surfaces of MXene nanosheets, their excellent water dispersion and strong interactions (hydrogen bond and electrostatic interactions) with polymeric networks endow the related hydrogel with excellent mechanical stretchability . In addition, the unique metallic conductivity of MXene nanosheets and large specific surface area will form continuously conductive pathways in hydrogels to render a high conductivity of the MXene-based hydrogels.…”

Effect of Annealing on Graphene/PVDF Nanocomposites

“…Recently, a new class of materials called MXene has been identified as a filler material in composite materials owing to important MXane’s properties such as tunability of properties choosing the metal component (M). MXene nanosheet-based hydrogel composites have been successfully developed to fabricate triboelectric nanogenerators . However, this material also has some challenges in application viewpoints such as the poor dispersibility of MXene nanosheets in the composites and instability of MXene in the presence of water vapor .…”

“…MXene nanosheet-based hydrogel composites have been successfully developed to fabricate triboelectric nanogenerators. 10 However, this material also has some challenges in application viewpoints such as the poor dispersibility of MXene nanosheets in the composites and instability of MXene in the presence of water vapor. 11 Another candidate for nanocomposite fillers is the carbon nanotubes, which have extremely high production cost and relatively low conductivity.…”

Flexible Piezoelectric Nanogenerator Based on Cellulose Nanofibril/MXene Composite Aerogels for Low-Frequency Energy Harvesting

“…In recent years, MXene has attracted broad research interests due to its unique sheet-like structure and excellent conductivity, which make it a promising material to fabricate flexible electronics, including human motion monitoring, human–machine interfaces, and gas- and humidity-sensing devices. − MXene refers to a family of two-dimensional (2-D) metal carbides/nitrides with a common formula M n +1 X n T x , where M is a transition metal (e.g., Mo or Ti), X is C or N, and T x represents the terminal groups on MXene such as −O, −OH, or −F . Because of the abundant surface groups, MXene is capable of establishing strong interactions with polar groups on polymer chains, thus rendering the bulk with reinforced mechanical strength and good self-healing properties.…”