A team at the University of Chicago, part of their Human Computer Integration Lab, has a new proposal for engineering interactive devices that integrate directly with the human body — topical stimulants applied directly to the skin as a way to render haptic experiences in VR. This use of sensation via chemical interaction with skin marks a new class of haptic device, which they are calling Chemical Haptics. Currently, the researchers have identified five chemicals useful in rendering lasting sensations: sanshool creates a tingling, lidocaine numbs, cinnamaldehyde provides a stinging sensation, capsaicin warms, and menthol cools.
This approach can be made viable in a variety of applications through a self-contained wearable device that can be worn anywhere. Their design is a soft silicone patch that uses micropumps to push the liquid stimulants through channels that open to the user’s skin, allowing the skin to absorb them as they pass through. On top of giving sensations not available through existing haptic devices, this also allows for multiple responses to be achieved through a single actuator.
The design was tested in five bespoke VR environments, a video of which is available on YouTube along with a clip of the talk presented at ACM UIST 2021. In a user study, participants rated the immersiveness of each VR experience with and without the utilization of chemical haptics; overwhelmingly, the small sample of participants indicated increased immersion with the use of the chemical haptic devices.
As this is a novel approach, the researchers also present recommendations on when and how to utilize chemical haptics, indicating that it is most suitable for “slow-changing haptic events” such as how the sting of a wound would evolve over the first few minutes or a slow rise in temperature. They also recommend adjustment of chemical concentration depending on the bodily location of the device, and how to prioritize chemical choice by the dominant sensation each chemical offers, as well as recommended safety precautions. All of this is available in the penultimate section of their recently published paper.
This brings a new possibility to the future design of VR experiences and haptic devices, pushing boundaries and emphasizing the role of sensations beyond vibration and pressure. The team sees it as a first step towards HCI research into the possibilities of chemically-actuated sensations on the skin. Since skin can be interfaced within this way, future work could fine-tune details of how these sensations are experienced, including transitions between sensations, mixing compounds and custom-engineering chemicals for a new sensation, and comparing these approaches to traditional methods.