While 3D printing can be used to create devices like prosthetics or smart pill bottles that can remind patients to take their medicine, this method doesn't easily allow for the ability to monitor how patients use those devices. "We're interested in making accessible assistive technology with 3D printing, but we have no easy way to know how people are using it," Jennifer Mankoff, a professor with the university's School of Computer Science & Engineering and a researcher on the project, said in a statement. "Could we come up with a circuitless solution that could be printed on consumer-grade, off-the-shelf printers and allow the device itself to collect information?" Turns out, they could.

The team noted that in order to convert these 3D printed objects into smart devices, they needed the ability to monitor complex actions and store data. Previously, their devices were able to track movement in one direction, like measuring how much liquid is poured out of a detergent bottle, for example. But that wouldn't be enough when you're trying to determine whether a pill bottle has been opened and closed. So this time, they incorporated two antennas into their objects, which can signal movement in two directions -- a method that can be applied to both smart pill bottles as well as prosthetics. You can see it put into action in the video above.

As for storing information, the team used the example of an insulin pen. "You can still take insulin even if you don't have a WiFi connection," said Shyam Gollakota, another scientist involved with the work. "So we needed a mechanism that stores how many times you used it. Once you're back in the range, you can upload that stored data into the cloud." For this, they put a spring inside of a ratchet, and every time a button is pushed, that spring gets tighter. When the user is back in the range of WiFi, they can release the ratchet and the spring will unwind, triggering a switch to touch an embedded antenna. Each button press will then be translated into an antenna contact, allowing frequency of use data to be transmitted.

Next, the team plans to make these prototype devices smaller, so that they can be embedded into actual pill bottles, prosthetics and insulin pens. The researchers will present their work later this month at the ACM Symposium on User Interface Software and Technology.