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.

Replicating real-world textures using haptic technology poses significant challenges, particularly in accurately capturing complex tactile qualities such as smoothness, roughness, and sharpness through vibration-based information. This research investigates how vibration parameters, intensity, duration, and off-time, can be manipulated to simulate textures inspired by fruit skins, including smooth-apple, rough-melon, bumpy-corn, sharp-pineapple, and adhesive-banana. Using a user-centered design methodology, we developed five vibrotactile patterns and implemented them within the Cactus Mobile Haptic Interface. The patterns were delivered via two interaction devices, a thimble and a stylus pen, designed to enable touch-based activities and tactile experiences. An empirical study with 36 participants evaluated those devices within three tasks: Tolerance to 10-second exposures, change perception, and the ability to associate patterns with real-world textures. Results showed that most patterns were accurately classified (76% with the thimble and 78% the stylus), although the adhesive texture proved more difficult to identify. Rough and sharp textures received slightly lower comfort ratings. While there were notable confusions between similar patterns, such as the sharp–bumpy pair, the type of interaction device did not significantly affect classification accuracy. These findings highlight the potential of low-cost haptic interfaces to mimic sensations from natural, realistic textures and emphasize the importance of refining vibration design for improved perceptual clarity. This work contributes to the development of accessible, portable, and customizable haptic systems designed for sensory interaction in therapeutic, educational, and interactive environments. Future research will focus on refining ambiguous patterns and exploring sensory integration to expand the system’s usability in tactile therapy.