Abstract: When we look back to the early days of computing, user and device were distant, often located in separate rooms. Then, in the ​’70s, personal computers ​“moved in” with users. In the ​’90s, mobile devices moved computing into users’ pockets. More recently, wearable devices brought computing into constant physical contact with the user’s skin. These transitions proved useful: moving closer to users allowed interactive devices to sense more of their user and act more personal. The main question that drives my research is: what is the next interface paradigm that supersedes wearable devices?

The primary way researchers have been investigating this is by asking where future interactive devices will be located with respect to the user’s body. Many posit that the next generation of interfaces will be implanted inside the user’s body. However, I argue that their location with respect to the user’s body is not the primary factor; in fact, implanted devices are already happening in that we have pacemakers, insulin pumps, etc. Instead, I argue that the key factor is how devices will integrate with the user’s biological senses and actuators.

This body-device integration allowed us to engineer interactive devices that intentionally borrow parts of the body for input and output, rather than adding more technology to the body. For example, one such type of body-integrated devices, which I have advanced recently, are interactive systems based on electrical muscle stimulation. These devices move their user’s muscles using computer-controlled electrical impulses, achieving the functionality of robotic exoskeletons without the bulky motors.

The key insight is that engineering devices that intentionally borrow parts of the user’s biology puts forward a new generation of miniaturized devices; allowing us to circumvent traditional physical constraints. For instance, in the case of our devices based on electrical muscle stimulation, they demonstrate how our body-device integration circumvents the constraints imposed by the ratio of electrical power and size of a motor (i.e., the stronger/larger a motor is, the more current needed to actuate it). 

Taking this further, we demonstrate how our body-device integration approach allowed us to also miniaturize thermal feedback (hot/cold sensations) without the need for power-hungry devices like Peltiers, air conditioners, or heaters. 

We believe that these bodily-integrated devices are the natural succession to wearable interfaces and allow us to investigate how interfaces might connect to our bodies in a more direct and personal way.