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Circuit-Free Cardiovascular Monitoring via Smartphone-Readable Skin-Interfaced Nanophotonic Films
Torjus L Steffensen1, Vegar Stubberud2, Emilie S Hennisen3
1Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway.
Advanced Materials (Deerfield Beach, Fla.)
|August 6, 2026
Summary
Researchers developed a new way to monitor heartbeats using a special film and smartphone cameras. This electronics-free method offers a promising approach for wearable health tech and diagnostics.
Area of Science:
- Materials Science
- Nanotechnology
- Biomedical Engineering
Background:
- Existing strain sensors for skin interfaces often require complex equipment.
- There's a need for electronics-free, easily readable sensing technologies for wearables.
Purpose of the Study:
- To develop a novel, electronics-free strain-sensing material for cardiovascular monitoring.
- To enable non-invasive pulse detection using unmodified smartphone cameras.
Main Methods:
- Fabrication of a dual-function poly-dimethylsiloxane (PDMS) film with a nanophotonic surface and 3D structural adhesive using nanoimprinting.
- Characterization of strain-dependent optical response and adhesive properties.
- Validation of the system using smartphone recordings in human subjects and comparison with clinical references.
Main Results:
- The PDMS film demonstrated stable, strain-induced RGB intensity modulation (2% strain produced 9% modulation over 1000 cycles).
- 3D structuring enhanced adhesive shear strength on skin by 65%.
- Smartphone recordings accurately captured sub-beat hemodynamics (waveform correlation ρ = 0.94 ± 0.03) and were independent of skin melanin content.
Conclusions:
- Camera-readable mechanochromic elastomers offer a versatile platform for cardiovascular monitoring.
- This technology overcomes limitations of existing photoplethysmography (PPG) methods.
- The developed system is suitable for wearable devices, point-of-care diagnostics, and human-machine interfaces.
