July 25, 2003 — Imagine your kitchen blender conks out the day you’re hosting a large cocktail party. You search an online catalog, decide on a model, and click the “buy” button. But instead of waiting three days for the appliance to be shipped to your door, a new kind of printer on your desk springs into action. Layer by layer, the miraculous machine squirts out various materials to form the chassis, the electronics, the motors — literally building the blender for you from the bottom up in a matter of hours.
Call it desktop manufacturing. For gadget geeks in need of instant gratification, it’s a miracle. For designers deep in the iterative prototyping process, it’s a revolution in product development. And thanks to small tech, it’s becoming a reality.
University of California, Berkeley engineering professor John Canny and his colleagues are building such a printer. They call the technology “polymer mechatronics” or, more simply, flexonics. The revolutionary approach to desktop manufacturing is enabled by recent advances in 3-D printers, organic electronics and polymer actuators.
Three-dimensional printers are commonly used to make prototypes of new product designs. For example, a designer may load a digital design into a Fused Deposition Modeling machine. The FDM then extrudes thin beads of ABS plastic in .01-inch layers, until you have a completed passive functional part or device. While the printers are dropping in price, the leap from producing passive to active devices is monumental. That’s where organic electronics come into play.
Organic electronics were born in the 1970s when researchers discovered that chemically doping organic polymers, or plastics, increases their electrical conductivity. Since then, researchers have worked to develop the most effective and inexpensive organic compounds that can be patterned on flexible substrates to create useful circuits. In the private sector, companies ranging from Bell Labs to IBM to UK startup Plastic Logic are also working to develop quality organic transistors that are fabricated far more cheaply than silicon circuits. Organic semiconductors will most likely first hit the market in the form of inexpensive radio-frequency identification (RFID) tags and flexible display screens.
Canny’s co-investigator in Berkeley’s flexonics effort, Vivek Subramanian, is one of many researchers harnessing the microfluidic precision of inkjet printing technology to deposit organic semiconductors in desired patterns. The key ingredient in Subramanian’s organic circuits is “liquid gold.” Synthesized in his laboratory, liquid gold consists of gold nanocrystals that are only 20 atoms across and melt at 100 degrees Celsius, 10 times lower than normal.
The gold nanocrystals are encapsulated in an organic shell of an alkanethiol (an organic molecule containing carbon, hydrogen and sulphur) and dissolved in ink. As the circuit is printed on plastic, paper or cloth using inkjet technology, the organic encapsulant is burned off, leaving the gold as a high-quality conductor.
Combining Subramanian’s circuit printing technology with a 3-D printer enables electronics to be embedded within the housing of the device being printed. The chassis and the electronics are fabricated as one single structure.
The next step is to add the actuators that provide electromechanical capabilities to the devices — for instance, a mechanism that causes the blender’s blades to spin when switched on. For this, Canny plans to fill inkjet cartridges with electroactive polymers that contract when zapped with a voltage, enabling components to flex in desired directions. Additionally, the polymers generate a voltage when compressed, so buttons and switches can also be embedded within the printed devices.
While Subramanian hones his organic semiconductors, Canny and his graduate student Jeremy Risner are designing a “vocabulary” of mechanical components — joints, grippers, transmission systems — suited for the 3-D printing process.
Flexonics is still in its infancy, but the technology’s potential raises questions about what it will mean to be a consumer in an era of devices-on-demand. You’d no longer pay for a product, Canny says, you’d pay for plans. I look forward then to a generation of do-it-yourself industrial designers, tinkerers who tweak commercial product designs to improve and customize them. How will I access the fruits of their labor? Peer-to-peer plan networks, of course, where designs for blenders and mobile phones and TV remote controls are swapped like so many MP3s.