Design and experimental validation of a soft pneumatic robotic device for preterm infant skin-to-skin tactile therapy

Skin-to-skin tactile stimulation plays a critical role in the neurodevelopment of preterm infants, contributing to improved physiological stability, sensory integration, and caregiver bonding. However, the delivery of consistent tactile therapy in neonatal intensive care units is often limited by the availability of trained personnel and the inherent variability of manual application. This creates a need for assistive technologies capable of reproducing clinically relevant tactile stimuli in a controlled and repeatable manner. This work presents a soft pneumatic robotic system designed to replicate clinically inspired tactile stimulation for neonatal therapy. The proposed approach integrates experimental characterization of manual tactile interactions, pneumatic system modeling, and closed-loop control. Force measurements obtained from a neonatology specialist were used to define clinically grounded stimulation levels, with mean values of 0.594 N for light stimulation and 1.267 N for moderate stimulation. These values were mapped to actuator pressure through experimentally identified linear relationships between force, pressure, and electrical current, enabling the definition of therapeutic pressure references. A 3 × 3 matrix of textile pneumatic actuators was integrated with an electro-pneumatic actuation system, pressure sensing, and current monitoring to implement the proposed therapy platform. Two control strategies were evaluated: a baseline pressure deadband controller and a refined deadband controller incorporating actuation tuning and current-based protection. Experimental results demonstrated that the refined controller increased the time within the therapeutic pressure band from 30.8% to 76.1%, while reducing mean pressure error from 0.68 kPa to 0.15 kPa and RMS error from 0.92 kPa to 0.38 kPa. Robustness tests under varying mechanical interface conditions showed stable and consistent pressure regulation performance. These results demonstrate the feasibility of translating clinically derived tactile stimulation into controlled pneumatic actuation using a soft robotic platform. By combining clinically grounded references, pressure-based closed-loop control, and safety-oriented current monitoring, the proposed system provides a reproducible and safe preclinical platform for neonatal tactile therapy and supports the development of assistive soft robotic technologies for clinically representative neonatal care environments.