Textile-integrated iontronic foam for scalable and robust pressure sensing in wearable systems

Flexible pressure sensors that are simple to manufacture, mechanically robust, and readily integrated with textiles are critical for the advancement of wearable health monitoring and human–machine interfaces (HMIs). This work reports a scalable, single-step route to such a sensor, fabricated from a commercially available fast-reaction foam (Flexfoam) cured directly onto conductive textiles and integrated with different concentrations of the ionic liquid (IL) 1-methyl-1-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([PMPyrr][TFSI]). Increasing IL content reduces the foam expansion ratio from ~600% to ~350% and reduces the Young’s Modulus from 208 ±10kPa for the pristine foam to 37 ±3kPa for the highest filler content of 40 wt% [PMPyrr][TFSI] concentration. At 40 wt% IL content, the sensing element retains 49% of the neat-foam peel strength to the conductive textile (0.51 ± 0.12 N/mm versus 1.04 ± 0.11 N/mm) and provides a moderate sensitivity of 0.29 ± 0.008 kPa⁻¹ over 0–50 kPa, a response and recovery time of ~72 ms and ~85 ms, and stable operation over 8000 loading cycles at 50 kPa. The sensor is demonstrated for respiration and jugular-pulse monitoring and, in a 3 × 3 matrix, for multi-touch HMI, rendering it a strong candidate for scalable, integrated wearable technology.