The Future of Haptic Technology: From Touchscreens to Ultrasound Beams

Haptic technology is the science and engineering of creating artificial touch sensations for human-computer interaction. Haptics can enhance the realism, immersion and performance of various applications, such as virtual reality, augmented reality, telepresence, gaming, education and health care. In this blog post, we will explore the current state and future trends of haptic technology, with a focus on a novel and promising modality: ultrasound haptics.

## What is Ultrasound Haptics?

Ultrasound haptics is a contactless haptic technology that uses focused ultrasound waves to create tactile sensations in mid-air. Unlike conventional haptic devices that require physical contact with the user's skin, ultrasound haptics can provide touch feedback without any wearable or handheld device. This enables users to interact with virtual objects and environments using their bare hands, feeling shapes, textures, forces and motions.

Ultrasound haptics works by using an array of ultrasound transducers that emit sound waves at frequencies above the human hearing range (typically 20-40 kHz). By controlling the phase and amplitude of each transducer, the sound waves can be focused and scanned in a three-dimensional space, creating pressure variations in the air that can be felt by the user's skin. Depending on the intensity and frequency of the ultrasound waves, different types of tactile sensations can be generated, such as tapping, pulsing, vibration and texture.

Ultrasound haptics has several advantages over other haptic modalities, such as:

- It is contactless and wireless, which reduces the risk of contamination and infection in medical applications, and increases the freedom of movement and comfort for the user.

- It is scalable and reconfigurable, which allows for creating large and complex haptic scenes with multiple focal points and dynamic shapes.

- It is compatible with other sensory modalities, such as vision and audio, which can create multisensory illusions and enhance the realism and immersion of virtual experiences.

However, ultrasound haptics also faces some challenges and limitations, such as:

- It has low spatial resolution and bandwidth, which limits the fidelity and variety of tactile sensations that can be rendered.

- It has high power consumption and noise emission, which can affect the safety and usability of the system.

- It has nonlinear effects and interference patterns, which can reduce the accuracy and stability of the haptic feedback.

## Applications of Ultrasound Haptics

Ultrasound haptics has been applied to various domains and scenarios, where contactless and reconfigurable touch feedback can enhance the user experience and performance. Some of the main application areas are:

- **Virtual reality (VR) and augmented reality (AR):** Ultrasound haptics can create immersive and realistic VR and AR experiences, where users can feel and manipulate virtual objects and environments with their hands. For example, ultrasound haptics can render the shape and texture of a virtual button ¹, the force and motion of a virtual ball ², or the temperature and wind of a virtual fire ³. Ultrasound haptics can also create multisensory illusions, where the haptic feedback is synchronized with visual and audio cues to enhance the perception of virtual phenomena, such as raindrops , fireworks , or holograms .

- **Telepresence and teleoperation:** Ultrasound haptics can enable remote communication and collaboration, where users can feel the presence and actions of other people or robots. For example, ultrasound haptics can transmit hand gestures , hugs , or heartbeats  between distant users, or provide haptic feedback from a remote robot arm  or drone . Ultrasound haptics can also facilitate social interactions, such as playing games , sharing emotions , or teaching skills .

- **Gaming and entertainment:** Ultrasound haptics can provide engaging and fun gaming and entertainment experiences, where users can feel the effects of their actions and interactions. For example, ultrasound haptics can simulate the recoil of a gun , the impact of a sword , or the explosion of a bomb  in a video game, or create haptic sensations that accompany music , movies , or stories .

- **Education and health care:** Ultrasound haptics can support education and health care applications, where users can learn and practice skills or procedures with haptic guidance and feedback. For example, ultrasound haptics can help users learn how to play a musical instrument , draw a shape , or perform a surgical task . Ultrasound haptics can also provide therapeutic benefits, such as pain relief , stress reduction , or sensory stimulation .

## Future Trends of Ultrasound Haptics

Ultrasound haptics is a rapidly evolving technology that has the potential to revolutionize human-computer interaction in various domains. However, there are still many challenges and opportunities for further research and development. Some of the future trends of ultrasound haptics are:

- **Improving hardware platforms:** The majority of ultrasound haptic devices currently being used, such as those produced by Ultraleap, are implemented using an array of 256 Murata MA40S4S transducers operating at 40 kHz. These are standard components that are commonly used in applications such as automotive parking and alarm sensors. However, these transducers have some limitations, such as low efficiency, high power consumption, high noise emission, and limited bandwidth. Therefore, there is a need for developing new hardware platforms that can overcome these limitations and enable higher quality and more diverse haptic sensations. Some possible directions include using higher frequency transducers (e.g., 100 kHz or 200 kHz) , using custom-designed transducers with optimized parameters , using metamaterials or acoustic lenses to enhance the focusing and steering capabilities , or using flexible or curved arrays to create more complex haptic shapes .

- **Developing new rendering algorithms:** The current rendering algorithms for ultrasound haptics are based on simple models that assume linear and isotropic propagation of ultrasound waves in air and skin. However, these models do not capture the nonlinear and anisotropic effects that occur in reality, such as shock wave formation, interference patterns, attenuation, scattering, and reflection. These effects can reduce the accuracy and stability of the haptic feedback, and also create new opportunities for creating novel haptic sensations. Therefore, there is a need for developing new rendering algorithms that can account for these effects and exploit them for enhancing the haptic quality and diversity. Some possible directions include using nonlinear acoustic solvers , using machine learning techniques , or using multisensory integration methods .

- **Enhancing user experience and value:** The ultimate goal of ultrasound haptics is to create meaningful and enjoyable user experiences that can add value to different applications and scenarios. However, there is still a lack of understanding of how users perceive and respond to ultrasound haptic feedback, and how it affects their behavior, performance, and satisfaction. Therefore, there is a need for conducting more user studies and evaluations that can provide insights into the human factors and design principles of ultrasound haptics. Some possible directions include studying the perceptual thresholds and preferences of users , exploring the emotional and social aspects of ultrasound haptics , or investigating the long-term effects and acceptance of ultrasound haptics .

Tweet

Read More..