Fabrication strategies to enable rapid prototyping of haptic devices and experiences
Embargo Date
2026-02-07
OA Version
Citation
Abstract
The skin, with its high density of specialized neurons, provides a rich platform for discrete communication through haptic feedback technologies. However, current manufacturing techniques for haptic devices are labor-intensive and require significant technical expertise, limiting accessibility and broader adoption. Existing processes involve specialized PCB software for circuit design, followed by multi-step integration into a soft polymer matrix, resulting in prolonged lead times and limited design flexibility. Furthermore, these devices typically rely on external computing units for controlling tactile patterns and intensity, often decoupling the two. This work proposes fabrication strategies ranging from benchtop 3D printing to hybrid techniques that integrate innovative materials with intuitive interfaces, enabling customizable and accessible haptic devices. We aim to create wearable haptic devices with direct, human-in-the-loop customization of haptic cues. To simplify the creation of haptic feedback devices, we developed a toolkit comprising five wireless, wearable haptic modules that deliver the three most common tactile sensations: vibrotactile, skin-stretch, and probing. These customizable modules can operate individually or together to create multimodal haptic experiences, serving as a platform for rapid prototyping tactile displays. However, despite their accessibility and ease of assembly, the modules remain bulky, rigid, and limited in customization, relying on an off-board computer and technical expertise to function. To create truly body-compliant stretchable haptic electronics, we developed a 3D printed liquid metal (LM) emulsion for wiring that sustains high strains while maintaining electrical connectivity. To fabricate stretchable electronics, the LM emulsion was integrated into a soft polymer matrix through multi-material 3D printing, with manually placed off-the-shelf electronics. The LM emulsion is not conductive upon printing but can be render highly conductive with a single axial strain at low stress (< 0.3 MPa), resulting in activation stresses that are an order of magnitude lower than previous work. The LM emulsion also exhibits a maximum conductivity that is more than 300% higher than that of similar previous work. Its high conductivity and durability under strain make it ideal for stretchable electronics. To integrate the LM emulsion into stretchable electronics, we developed a computer aided fabrication strategy that streamlined the design and production of haptic devices. First, we created an intuitive graphical user interface (GUI) for sketching haptic devices, compatible with direct ink writing. Next, we developed an algorithm to convert circuit schematics into 3D printing commands. This strategy combines direct ink writing with automated pick-and-place of electronics in a single fabrication step. Using this process, we fabricated a wireless, self-powered tactile display comprising a haptic input device and a haptic output device. Together, these devices enable immersive human-to-human interactions by mapping real-time pressure patterns through the input device and generating proportional vibrotactile feedback with the output device. This approach represents a significant step toward enabling rapid prototyping of both haptic devices and haptic experiences.
Description
2025
License
Attribution 4.0 International