Whenever I pick up a package of frozen raw meat from the grocery store, I wonder, “Has this been frozen the whole time? How many times did it thaw and re-freeze?” It’s a disquieting thought, especially because there’s currently no easy way to tell.
But it looks like the ambiguity is about to end. In partnership with PST Sensor, Thinfilm, which produces printed re-writable memory, will begin making the first fully printed temperature sensor systems to monitor perishable items like food and pharmaceuticals.
“It’s a smart object that’s entirely self-contained,” Jennifer Ernst, Thinfilm’s North American VP told Wired.
That may sound familiar. It’s a key element of a concept called “The Internet of Things,” which basically refers to an imagined future where nearly every object will include embedded chips that can store data and interact with networks.
Thinfilm’s first-gen sensors will be able to cache data about the object itself, on the item itself. In this case, the sensors will record data concerning the object’s temperature history, tracking precise time, temperature and exposure information, and also displaying it in a low-power readout. The data within can be accessed as needed, insomuch it doesn’t need to be retrieved from the cloud, or require a constant wireless connection.
In the past, we’ve seen thin food sensors that change color as food begins to spoil. But this type of technology doesn’t retain data, and thus doesn’t provide information about the history of a product as it shipped.
Unlike the simple color-changing strips, ThinFilm’s technology is composed of a few different components: a temperature sensor (called a thermistor), a battery, addressable memory, and an optional contact-based readout or display. The printed temperature sensor took 10 years of development to become a reality. The entire circuit should be able to last for six months or more, drawing less than 0.2 microamps of current from its 3-volt, 1-mAhr battery.
Thinfilm’s technology is also different from existing systems that contain or beam out information. RFID sensors, for example, cost up to $100 to create, and with traditional semiconductor manufacturing, there’s a lot of waste involved.
But Thinfilm prints organic circuits. They’re inexpensive, flexible, and generally disposable. In fact, the system’s memory is made from a ferro-electric polymer that’s completely disposable. The material from the transistor follows familiar CMOS style-circuitry. The result is a sensor that should only cost about 30 cents when the product starts deploying circa 2013, and will become even cheaper in the years following.
So, what would something like this look like?
Thinfilm already prints transparent, thin and flexible 20-bit memory (pictured above) that’s used in toys and games. This sensor would be similar.
“It will be very much like a sticker, with a lot of functionality,” Ernst said. “It’s a thin layer of plastic with electrodes, and memory film on top of it.”
Besides keeping track of perishable food items, the temperature sensors could also be placed on vaccines or vials of medicine to ensure they’re stored at safe temperature levels throughout transport to hospitals or doctors offices.
In the future, this type of technology could also be applied to other kinds of sensors, like humidity sensors. Thinfilm is building out a digital ecosystem, so safe, disposable, cheap sensors could be used in all sorts of applications.