Article Highlight | 31-Dec-2025

Boosting sensitivity of cellulose pressure sensor via hierarchically porous structure

Shanghai Jiao Tong University Journal Center

Boosting Sensitivity of Cellulose Pressure Sensor via Hierarchically Porous Structure

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  • The study introduces a high-performance cellulose hydrogel (HPCH) with a biomimetic layered porous structure inspired by human skin, combining a soft layer with large macropores and a hard layer with small micropores. This unique design enhances both sensitivity and mechanical performance in pressure-sensing applications.
  • The HPCH sensor demonstrates exceptional pressure sensitivity of 1622 kPa⁻1, a wide detection range of up to 160 kPa, and excellent conductivity of 4.01 S m−1. Ion immersion further optimizes the hydrogel’s conductivity and dielectric properties, offering superior performance compared to existing cellulose-based sensors.
  • The sensor’s outstanding performance in health monitoring, industrial diagnostics, and pressure distribution detection positions it as a versatile, durable, and highly sensitive solution for various pressure-sensing applications, providing a promising path for natural polymer-based sensing technologies.
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Credit: Minzhang Chen, Xiaoni An, Fengyan Zhao, Pan Chen*, Junfeng Wang*, Miaoqian Zhang, Ang Lu*.

Conventional plastic or silicone pressure sensors deliver either high sensitivity or a wide range—but rarely both. Now, researchers from Wuhan University and Beijing Institute of Technology—Prof. Ang Lu, Prof. Pan Chen and Prof. Junfeng Wang—report a fully biodegradable cellulose hydrogel that mimics human skin’s layered dermis, achieving a record 1,622 kPa-1 sensitivity while maintaining a 160 kPa detection window and 33 ms response time for wearable health and industrial diagnostics.

Why the HPCH Sensor Matters
• Bio-Inspired Hierarchy: A soft macroporous layer (low modulus) detects gentle touches; a hard microporous layer (high modulus) prevents collapse under heavy loads—merging the best of both worlds.
• Ion-Enhanced Dielectrics: Simple soak in trisodium-citrate boosts relative permittivity and forms electric-double-layer capacitance, lifting sensitivity 900 % versus neat cellulose.
• Green & Recyclable: Made from cotton-linter pulp, cross-linked with epichlorohydrin and reusable after 5,000 cycles—addressing sustainability demands of next-gen wearables.

Innovative Design & Features
• Material System: Two-step emulsion/centrifugation casts a 2 mm bilayer—top layer ~300 µm pores for deformation, bottom layer sub-10 µm pores for support; final density 0.18 g cm-3.
• Conductivity Engineering: KCl immersion yields 4.01 S m-1 ionic conductivity—ten-fold higher than typical nanocellulose films—while preserving 250 % elongation and 1.6 Pa detection limit.
• Device Architecture: Capacitive sensor (Ag electrodes, 1 kHz) packaged in 0.5 mm VHB tape; operates 5–45 °C, 30–90 % RH with <3 % drift.

Applications & Future Outlook
• Health Monitoring: Wrist-attached patch resolves individual P-, T- and D-wave peaks of radial pulse (68 bpm) for real-time arterial-stiffness assessment; eyebrow sensor tracks micro-expressions for emotion AI.
• Machine Fault Diagnosis: Mounted on hair-dryer or vacuum pump, the hydrogel converts vibration anomalies into capacitance wavelets, enabling early blockage alerts before audible noise occurs.
• Smart Insole: 4 × 4 array molded into shoe insole maps plantar pressure during heel-strike, mid-stance and toe-off; differentiated pressure profiles promise gait-correction footwear and sports analytics.
• Scalability & Roadmap: Roll-to-roll slot-die trials are underway for 30 cm-wide sheets; team is exploring citrate-free food-grade cross-linkers and lamination on textile yarns for machine-washable e-garments.

This work demonstrates that hierarchical porosity and benign ionic chemistry can transform the planet’s most abundant biopolymer into an elite sensing material—opening a sustainable route for skin-like electronics, soft robotics and green IoT.

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