Table 5.

List of self-healing mechanisms, along with some of their structure design properties.

SN	Structure Design	Sensor Type	Self-Healing Mechanism	Self-Healing Material/Agent	Self-Healing Time (h)	Note
1.0	(f-BN NS)/PEDOT: PSS/PNIPam Hydrogel [469]	Pressure	Chemical bond interaction-based (Hydrogen-bond)	-	6.0	The self-healing starts at room temperature.
2.0	Ag NWs/rGO@m-PCL Microspheres onto PDMS [481]	Strain	Solid Microsphere	Ag NWs/rGO@m-PCL Microspheres	0.05 (3.0 min)	Heated at 80 °C for 1 min, then, self-healed for 3 min with a cut of 10 µm size. Acceptable conductive stability (25% drop in resistance) and sensitivity (0.16 rad−1 in bending downward direction) under cyclic bending.
3.0	MWCNT-PEDOT-PAM-PVA [482]	Pressure	Chemical bond interaction-based (Hydrogen-bond)	-	~1 s	The self-healing property of the hydrogel was evaluated by restoring conductivity (i.e., ~96.0%) instantly.
4.0	Au NP/Sh-crl-PU [483]	Gas analytes, pressure, strain, and temperature	Chemical bond interaction-based (Hydrogen-bond)	-	48.0	The self-healing time of a cutting groove of ~ 150 µm was 30 min at room temperature. For compete cut into two pieces, it requires 48 h. Self-healing can occur between −20 °C–50°C After self-healing, composite recovered ~ 90% of tensile strength and ~97% of elongation in comparison with pristine Sh-Crl-PU.
5.0	(Ti3C2Tx)/PV) hydrogel [484]	Strain	Chemical bond interaction-based (Hydrogen-bond)	-	~0.15 s	Instantaneous self-healing is ~0.15 s at room temperature. This sensor maintains its original performance after a self-healing.
6.0	PAA slightly crosslinked with PEG Ionic Conductive Ink [470]	Strain	Chemical bond interaction-based (Ionic Interaction)	-	0.5	The self-healing time was 30 min at room temperature when the hydrogel is cut into two pieces and then reattached to each other even if directions of the two pieces were changed.
7.0	Ternary Composite DMSO-mixed PEDOT: PSS with Triton X-100 Wearable thermoelectric generators [485]	Strain	Chemical bond interaction-based (Hydrogen-bond)	Triton X-100 >(C14H22O(C2H4On)	1.0 s	The self-healing behavior was observed with the film thickness ≥20 µm and cutting width ≤100 µm.
8.0	PETMP-TTT Thiol-Ene Coatings [424]	-	Other Strategies (Shape memory assisted with heat)	-	0.083 (5.0 min)	Scratches produced on the PETMP-TTT polymer coatings with different constant loadings (1.2 N, 1.5 N, and 2.7 N) were completely self-healed after heating to 70 °C for 5 min. The crosslinked PETMP-TTT polymer network was also capable of initiating scratch recovery at ambient temperature conditions.
9.0	Conductive Polyimine Film (Dynamic Covalent Thermoset Polyimine with Ag NPs) [486]	Flow, humidity, tactile, and temperature	Other Strategies (Chemical Reaction assisted with heat and pressure)	Re-healing agent (TAA-DETA-TREN with EToH and Ag NPs)	4.0	The self-healing starts instantly. Heat-press (4 h at 80 °C and 8.5 kPa) was adopted to make the rehealed area more uniform and robust. This sensor is recyclable, too.
10.0	Stacked textile reinforcement with dual-channel [487]	-	3D Micro-vascular Networks	A mixture of DGEBA and Aliphatic amido-TETA	48.0	Two patterns of microvascular networks were applied (i.e., Parallel, and Herringbone). Herringbone pattern enhances mixing through increased interfacial and overlapping fluid boundary layers. Self-healing starts at 30 °C. Evaluation of continuous self-healing cycle.
11.0	rGO based Composite [488]	Pressure and flexion	Encapsulation	PBS confined in rGO networks with microscopic porosity	24.0	The self-healing and full-recovery start at ambient temperature for both mechanical and electrical properties.
12.0	Self-healing magnet-polymer composite [489]	Strain	Other Strategies (Shape memory assisted with a magnet)		0.167 10.0 min	The self-healing starts at ambient temperature when placing the torn edges of a test sample together between two glass slides while applying a magnetic field with an operating frequency of 475 kHz. Healing time is 10 min. Mn-Zn ferrite magnetic filler can trigger actuation, self-healing, and multiple cycle damage sensing.