In a time where connected devices and IoT are becoming increasingly mainstream, the idea of an object that tracks information is not wholly surprising. If, however, I told you that the object tracking the information did not integrate any electronics or batteries, I’d certainly expect some quizzical looks. But that’s exactly what researchers from the University of Washington have achieved in a recent research project involving 3D printed objects that can monitor how they are used.
The innovative research is a follow-up to a project that caught our eye in December of last year in which the same team of researchers 3D printed objects that could connect to WiFi without any electronics. In this project, they demonstrated how a laundry detergent fitted with a 3D printed bolt-on flowmeter could track when the fluid was running low and could automatically order more online.
Connected 3D printed devices
With their recent work, the researchers are aiming to show how 3D printed objects, such as assistive devices, fitted with small antennae can communicate vital information. For example, the team has 3D printed a prototype of a “smart” pill bottle which can track how often the bottle has been opened and can help to remind patients to take their medication.
“We’re interested in making accessible assistive technology with 3D printing, but we have no easy way to know how people are using it,” commented co-author Jennifer Mankoff, a professor in the UW’s Paul G. Allen School of Computer Science & Engineering. “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? That’s what we showed was possible in this paper.”
Shyam Gollakota, an associate professor in the Allen School and senior author of the study, added: “Using plastic for these applications means you don’t have to worry about batteries running out or your device getting wet. That can transform the way we think of computing. But if we really want to transform 3D printed objects into smart objects, we need mechanisms to monitor and store data.”
Tracking bidirectional information
In overcoming the challenges of monitoring and storing date, the team utilized a method called “backscatter,” which uses antennae to reflect WiFi signals and transmit certain types of information. In the case of the pill bottle, however, the researchers also needed to figure out how to transmit bidirectional motion (opening and closing the bottle) rather than unidirectional motion, which they had addressed in their previous project.
“Last time, we had a gear that turned in one direction. As liquid flowed through the gear, it would push a switch down to contact the antenna,” elaborated lead author Vikram Iyer, a doctoral student in the UW Department of Electrical & Computer Engineering. “This time we have two antennas, one on top and one on bottom, that can be contacted by a switch attached to a gear. So opening a pill bottle cap moves the gear in one direction, which pushes the switch to contact one of the two antennas. And then closing the pill bottle cap turns the gear in the opposite direction, and the switch hits the other antenna.”
To ensure that the information transmitted in both directions was identifiable, the team made slight changes to the gears in the mechanism, so that the antenna would hit the side to create a sequential pattern, not totally unlike morse code.
Another application where the data transmission could be useful is in 3D printed prosthetic hands, such as those made for children by e-NABLE. Rather than track how many times a bottle has been opened and closed, integrating the gears and antennae onto a 3D printed prosthetic can help to monitor how people are using the prosthetics.
The team has already 3D printed an e-NABLE arm with a bidirectional sensor built into it which is capable of monitoring when the hand opens and closes and what the angle of the wrist is.
Lost your connection? That’s OK
The team also created a 3D printed insulin pen prototype which can store information about its usage even when it is not in WiFi range. “You can still take insulin even if you don’t have a WiFi connection,” Gollakota explained. “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.”
This clever information storing technique involves a mechanical movement (like pushing a button on the insulin pen) each time the device is used. This motion rolls up a spring inside a ratchet that only moves in a single direction. When the button is pushed, the spring gets a bit tighter and the only way it can be released if if the user manually releases the ratchet.
This means that the user can simply wait until their are back in range of the backscatter sensor to release the ratchet. As the spring unwinds, a gear with an antenna is triggered which transmits the information to the cloud.
Still in the prototyping stage, the University of Washington researchers are planning to further refine the data tracking and storing devices by shrinking them down so they can be embedded into commercial pill bottles, prosthetics or insulin pens.
“This system will give us a higher-fidelity picture of what is going on,” Mankoff said. “For example, right now we don’t have a way of tracking if and how people are using e-NABLE hands. Ultimately what I’d like to do with these data is predict whether or not people are going to abandon a device based on how they’re using it.”
The research team will be presenting its innovative project next week at the ACM Symposium on User Interface Software and Technology in Berlin.