Twinkle trace: A customizable haptic interface for sensory engagement in children with ASD

Children with Autism Spectrum Disorder (ASD) often experience difficulties with tactile sensory processing, which can hinder their participation in daily activities and therapeutic interventions. To address this challenge, we introduce Twinkle Trace, a haptic interface designed to support engagement in classroom-based sensory activities. The system combines a crayon-like stylus, a tablet application to simulate crayon rubbing on textured surfaces using customizable vibration patterns inspired by familiar fruit textures: smooth (apple), rough (melon), bumpy (corn), sharp (pineapple) and adhesive (banana). Twinkle Trace includes a variety of interactive activities, such as free drawing, shape coloring, tactile scene coloring, tracing, and bubble popping, commonly used to promote sensory and fine motor control. We conducted a four-week classroom deployment study with six children with ASD using a comparison within-subjects against traditional crayon rubbing on textured surfaces. Therapist-rated engagement scores showed consistent directional trends favoring Twinkle Trace sessions over traditional activities, particularly in satisfaction, completion, and transitioning. Therapists progressively integrated the tool into daily routines, adapting it to weekly themes and individual needs. These findings suggest that embedding vibrotactile feedback within structured classroom exercises is associated with increased engagement and therapist appropriation in real-world special education contexts. Twinkle Trace provides a classroom-ready haptic system that integrates digital texture generation with therapeutic interaction design.