Italian researchers at the Istituto Italiano di Tecnologia (IIT) have created an ultrathin electronic tattoo with the capability to replicate localized sensations of touch. The device, made from temporary transfer tattoo paper, offers potential applications in lightweight, portable haptic displays and healthcare/robotics devices.
Touch is crucial for object manipulation, environmental interaction, and human-machine communication. Wearable devices simulating tactile sensations could benefit amputees controlling robotic arms, provide information to visually impaired individuals, and enhance experiences in virtual reality and gaming.
The researchers selected temporary transfer tattoo paper due to its efficient transfer to non-planar surfaces, enabling conformable electrodes and electric paths that adhere well to human skin. The paper was coated with a 1-micrometer-thick parylene layer for mechanical strength, and ultrathin films of conductive silver ink were directly printed onto it. Wiring and polystyrene microparticles were added to create tiny air-trapping spaces, with an additional parylene layer on top.
The device, a few micrometers thick, utilizes electro-thermo-pneumatic stimulation. Fast, localized electrical heating creates a small enclosed air volume between the parylene layers, generating forces felt by the skin upon contact with the device.
Testing on a glass slide and a human fingertip demonstrated the device’s effectiveness, with the subject feeling nine out of 10 stimulations and reporting no pain or temperature increase. The device operated on a small battery at low voltages (less than 300 mW), ensuring wearer safety.
The researchers showcased a single taxel (TActile pixel) that recognizes pressure contact with physical objects. Future plans involve developing larger tactile displays with multiple taxels for independent activation, allowing the reproduction of letters, numbers, and patterns on the skin.
While the current focus is on a single taxel, the researchers believe their approach, materials, and fabrication techniques could extend to more complex devices, envisioning the creation of larger tattooable tactile displays. Overall, this innovative ultrathin electronic tattoo holds promise for developing lightweight, portable haptic displays and devices in various fields.