In the late 1990s, the Tamagotchi handheld digital pets quickly rose to become one of the biggest toy fads of the time. There was something very addictive about the idea of caring for the virtual pets by clicking on buttons to feed them, give them medicine, or play with them. After all, failing to properly care for your cute, cuddly little pet would lead to it getting sick and ultimately dying. How sad! But by now, nearly all of those Tamagotchis are long forgotten, with the novelty having worn off long ago. So long, Fluffy, no time for you any more!
But it is only a virtual pet, so of course clicking buttons to pretend to “care” for a computer program will not be entertaining for long. People do not form attachments to, or feel a sense of responsibility towards, such things like they do a living organism. A duo of researchers at the University of Chicago had the idea to leverage our innate desire to care for our fellow living beings to alter peoples’ attitudes towards their interactive electronic devices. They tested out this concept by building a smartwatch containing a living organism that must be regularly cared for in order for the watch to function.
The hardware components (📷: J. Lu et al.)
The watch is not much to look at, with a very large, blocky 3D-printed case, but that is forgivable for a prototype. Inside the case is a SAM D21-based Seeeduino Xiao microcontroller, a MAX3010 heart rate sensor, an OLED display, a physarum sensing circuit, and some supporting hardware. The components come together to serve as a heart rate monitor, but with a twist — notice the physarum sensing circuit in the hardware list. For those unfamiliar, physarum are the sort of cute little animals everyone loves to visit in the pet store. Surely you have heard the children’s song called How Much Is That Physarum in the Window?
You have probably run a web search for “physarum” by now, so the secret is out — it is a slime mold that is anything but cute. Coming across this slime mold would tigger most people to reach for the nearest bottle of bleach. But the creators of this watch are hoping that people will form an attachment to the device by being responsible for caring for the organism. Feeding the slime mold water and oats will keep it healthy and allow it to grow in its enclosure that spans a pair of electrodes. When it is healthy, it acts as a conductive wire that closes this circuit; when it is not healthy, it dries up and goes dormant, breaking the circuit. The heart rate monitor is designed to only function when the physarum is healthy and closing the circuit. About two feedings per day are needed to maintain good health.
Physarum in various stages of health (📷: J. Lu et al.)
To see how well people take to caring for a slime mold smartwatch, a small study was conducted with five participants. They were asked to wear the watch for nine to fourteen days and go through two phases — care and neglect. Somewhat surprisingly, participants generally reported that they had developed some connection to the slime mold and thought of it like a pet. Some even expressed that they would like to continue wearing the watch. Given this feedback, perhaps there is some practical use for such a device. However, the use case presented — a heart rate monitor that breaks if you forget to feed your slime mold twice a day — does not sound like a big commercial hit. Time will tell if any more practical use cases arise, but if not, it could revive the Tamagotchi craze in a big way if incorporated into a toy.