Zhang, Y., Hu, Y., Zhu, Z., Montelongo, Y., Liu, Y., Waqar, S., Park, Y. S., Chan, L. C., Jiang, N., & Yetisen, A. K. (2025). Holographic hydrogel bandage sensor for continual monitoring of wound healing. Sensors & Diagnostics, 4(9), 736–749. https://doi.org/10.1039/d5sd00047e
Abstract:
Chronic wounds pose serious health and economic challenges. A low calcium (Ca2+) ion concentration during the early stage often indicates infections. Holographic hydrogel sensors offer label-free sensing platforms, providing real-time and continuous detections of analytes upon diffractive wavelength changes detectable by the naked eye or spectrophotometers, improving the Ca2+ ion concentration quantification accessibility. Herein, we present a holographic Ca2+ ion bandage sensor using carboxylate-containing hydrogels on polydimethylsiloxane (PDMS) substrates for real-time wound-healing assessment through smartphone readout. Simulations are conducted to investigate the effects of mechanical strength on sensitivity. The holographic Ca2+ ion sensor replays blueshifts of 35 nm (hue value change of 7) with 0–4 mmol L−1 Ca2+ ions, changing colors from dark red to red within 7 minutes. It can accurately and stably (over 24 hours) measure Ca2+ ions when bent. The stiffness of PDMS was tuned to balance comfort and sensitivity. In point-of-care settings, holographic bandage sensors, comprising the holographic hydrogel sensor, a backing layer, and a dark cotton layer, can continuously monitor Ca2+ ions over 10 hours via a smartphone application using hue values. A guiding square in the application assists users in capturing pictures within the inherently narrow viewing angle range of 20–33°. This holographic Ca2+ ion bandage sensor facilitates personalized wound assessment through colorimetric interrogation via smartphone readout.
License type:
Attribution 4.0 International (CC BY 4.0)
Funding Info:
There was no specific funding for the research done