Product Safety
AquaCare+ patches are made with natural, skin-friendly hydrogels and safe, non-toxic color-changing dyes designed for everyday use. We prioritize comfort, biodegradability, and gentle materials so caregivers can trust every patch they apply.
Our collaborating partner:
Chinese Academy of Science
We are honored to collaborate with researchers from the Chinese Academy of Sciences, whose expertise in biomaterials and polymer engineering has been instrumental in advancing the scientific foundation of the AquaCare+ hydrogel patch. Their support allowed us to rigorously analyze the patch’s microstructure, mechanical behavior, and chromogenic responsiveness using state-of-the-art laboratory techniques.
Material Safety
01
Anthocyanin
Anthocyanins are natural pigments extracted primarily from blueberries, red cabbage, purple carrots, etc. They function as pH-sensitive indicators, changing color in response to variations in acidity, making them useful for visual detection of chemical changes.
02
Curcumin
Curcumin is a natural polyphenolic compound extracted from turmeric roots. It functions as an electrolyte-sensitive indicator, changing color in response to ions, and is often used in colorimetric sensing applications.
03
Sodium alginate
Sodium alginate is a biopolymer extracted from seaweed. It serves as a hydrogel-forming material, providing a biocompatible matrix that can crosslink with divalent ions to form a stable gel network.
04
Chitosan
Chitosan is a natural polysaccharide derived from shrimp/crab shells. It enhances hydrogel mechanical strength and biocompatibility, and can participate in hydrogen-bond-assisted crosslinking to stabilize the gel network.
05
Calcium chloride
Calcium chloride is an inorganic salt used as a crosslinking agent. It interacts with sodium alginate to form ionic crosslinks, creating a stable hydrogel structure with uniform pores.
Experimental Data
Cell Viability
The two bar graphs measure cell viability (%) after exposure to the SCCA hydrogel compared with a negative control (no toxic treatment) and a positive control (cytotoxic agent). In both the 24-hour and 48-hour assays, the SCCA hydrogel maintains cell viability at levels nearly identical to the negative control (~95–100%), indicating excellent biocompatibility. In contrast, the positive control shows a dramatic drop in viability (approximately 20–25%), confirming the assay’s sensitivity and validating the comparison.
Statistical analysis shows no significant difference (ns) between the SCCA hydrogel group and the negative control at both time points, demonstrating that the hydrogel does not harm cells even after prolonged exposure. Meanwhile, the comparison between negative and positive controls shows **** (p < 0.0001), confirming strong statistical significance and establishing the expected toxicity profile.
Hydrogel Microstructure and Surface Morphology
1. Pore Size and Distribution:
SEM imaging reveals a high density of interconnected pores with individual pore diameters predominantly in the 80–120 μm range, consistent with the intended structural design. The absence of oversized cavities or densely packed nonporous regions indicates that ionic crosslinking (Ca²⁺–alginate) combined with hydrogen-bond–assisted crosslinking (chitosan–alginate) produced a uniform three-dimensional network. The pores exhibit excellent interconnectivity with no isolated closed pores, a critical feature for rapid diffusion of sweat components. This architecture ensures that perspiration can readily permeate the hydrogel matrix and interact efficiently with the embedded chromophores—anthocyanins (pH-responsive) and curcumin (electrolyte-responsive)—thereby maintaining high colorimetric sensitivity.
2. Matrix Surface Morphology: Under SEM, the hydrogel matrix displays a continuous fibrous or lamellar surface morphology without evidence of particle aggregation, confirming the homogeneous dissolution of anthocyanins and the uniform dispersion of curcumin microcapsules (5–10 μm) within the network. The smooth, burr-free matrix edges reflect complete crosslinking (rapid CaCl₂ ionic gelation followed by 37 °C curing to stabilize hydrogen-bond interactions), consistent with the physical characteristics previously described for a “semi-transparent, elastic hydrogel.” 3. Structure–Function Relationship: Pore-size suitability: The 80–120 μm pore dimensions are orders of magnitude larger than the primary sweat constituents—water molecules, Na⁺/K⁺ ions, and small organic acids (all
Mechanical and Viscoelastic Properties of the Hydrogel
1. Intrinsic Mechanical Behavior: Elasticity-Dominated Viscoelastic Material
Across the entire tested frequency range, the storage modulus (G′, elastic component) consistently exceeds the loss modulus (G″, viscous component), indicating that the hydrogel behaves predominantly as an elastic solid. This response is characteristic of a crosslinked polymer network capable of maintaining mechanical stability, resisting permanent deformation, and preserving structural integrity under stress.
2. Frequency-Dependent Response: Competition Between Molecular Mobility and Network Rigidity G′ increases monotonically with frequency: At higher frequencies, the polymer chains and crosslink junctions lack sufficient time to relax, causing deformation to be dominated by elastic strain (analogous to the rapid recoil of a rigid network). This suggests that the material can provide reliable mechanical support under dynamic loading conditions, such as during handling, motion, or application to moving tissue. G″ exhibits a “rise–fall” relaxation peak: - Low-frequency region (f 8 Hz): Molecular mobility becomes increasingly restricted (“frozen”), reducing viscous dissipation and causing G″ to decline. The peak in G″ corresponds to the characteristic relaxation frequency—where molecular relaxation rates and applied deformation frequency coincide—revealing the presence of dynamic structural features such as reversible cross-linking and chain-segment mobility.