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Printable and E-Tattoo Wireless Strain Sensors

Printed electronicsE-tattooNFC/RFStrain

Overview

This research develops a family of printable and e-tattoo wireless strain sensors for structural health monitoring of composite structures. The two formats share the same sensing idea—strain-dependent electrode resistance that reshapes the capacitive/RF response—while spanning routes from fully printed patches to ultra-thin transferable tattoos.

At the device level, interdigitated electrodes are modeled as a distributed RC network. Under low resistivity the AC signal spans the full electrode length; as strain raises electrode resistance, voltage attenuates along the fingers and the effective sensing length shrinks. That mechanism appears experimentally as a strong, frequency-dependent shift in effective capacitance and, in wireless LC tags, as a clear resonance-frequency shift under near-field readout—unlike control devices built with only conductive electrodes.

Building on this principle, fully printable sensors enable highly sensitive wireless near-field interrogation, while e-tattoo variants are fabricated as ultra-thin, transferable films that conform to textured and curved composite surfaces. Frequency-modulated printed capacitive sensing further improves sensitivity and linearity. The devices have been integrated with flexible wireless readout electronics for real-time SHM demonstrations, and the printable-sensor work received the Best Poster Award at LOPEC 2024.

Highlights

  • Piezoresistive IDE electrodes that convert strain into a distributed RC / frequency-response change
  • Fully printable LC wireless strain sensors with sensitive near-field resonance readout
  • Ultra-thin e-tattoo formats transferable onto textured and curved composites
  • Frequency-modulated printed capacitive sensing for higher sensitivity and linearity
  • Flexible wireless readout demonstrated for real-time SHM
  • Best Poster Award, LOPEC 2024

Videos

  • Fabrication and Transfer Process for E-Tattoo Sensors

    Fabrication and transfer process for e-tattoo wireless sensors.

  • Real-time SHM with Flexible Printed Sensors and IoT Circuits

    E-tattoo strain sensor integrated with a flexible wireless readout circuit for real-time structural health monitoring.

Figures

Interdigitated electrode capacitive sensing: lumped-element model and strain-dependent frequency response under low- and high-resistivity electrode conditions.
Interdigitated electrode capacitive sensing: lumped-element model and strain-dependent frequency response under low- and high-resistivity electrode conditions.
Wireless LC strain sensor with piezoresistive IDE electrodes: near-field readout, resonance shift with strain, and comparison with conductive-electrode controls.
Wireless LC strain sensor with piezoresistive IDE electrodes: near-field readout, resonance shift with strain, and comparison with conductive-electrode controls.
Fabrication and transfer of ultra-thin e-tattoo sensors, with conformal integration on textured and curved composite surfaces.
Fabrication and transfer of ultra-thin e-tattoo sensors, with conformal integration on textured and curved composite surfaces.

Related publications

  • A Fully Printable Strain Sensor Enabling Highly-Sensitive Wireless Near-Field Interrogation
    H. A. Mahmoud, H. Nesser, G. Lubineau · Advanced Science (2025) · [link]
  • Integrated Piezoresistivity and Frequency Modulation for High Sensitivity Printed Capacitive Strain Sensing
    H. A. Mahmoud, H. Nesser, G. Lubineau · IEEE FLEPS (2024) · [link]
  • Printed E-Tattoo Wireless Sensor for Smart Monitoring of Composite Structures
    H. A. Mahmoud, O. Khalifa, Y. Shi, A. Wagih, T. Y. Al-Naffouri, G. Lubineau · EWSHM 2026 (2026) · [link]

Awards

  • Best Poster Award, LOPEC 2024
    Best Poster Award, LOPEC 2024