For years, there have been scads of applications and gizmos based on piezoelectric materials. Nevertheless, I am often intrigued when I see smart use of the stuff. What has most recently grabbed my attention is a ventilating system featured in the new video from GE Global Research showing off the company’s Digital Cooling Jets (DCJ).
In a press release, GE describes the developments of the DCJ units as “a major technology breakthrough,” and now has patented it. While clever, describing the DCJ as a major breakthrough (more on this below) sounded to me like market hype, but I may be underestimating the engineering that had to go into this. Nevertheless, for sheer problem-solving simplicity, the DCJ is ingenious.
It appears to me that each half of a DCJ basically is made by taking a square of a multilayer piezo material, slapping on a nickel disk (which serves as an electrode) and connecting an ac current to the disk. Clamp two of these units together with a spacer between them, synchronize the current and—voila!—a mini piezo-based bellows.
While nifty in isolation, it is not clear to me where GE thinks the best markets for DCJ technology are. From the video, it is evident that GE sees a market in incorporating DCJ technology to control airframe surface and aircraft electronics temperatures. So, it is easy to jump from aircraft cooling to general computer cooling, such as the laptop ventilation application that is also demonstrated.
However, the video also suggests several different form factors and sizes. For example, the basic DCJ unit is the most bellows-like: air (or another gas) is pulled in and expelled from the same port. However, the airframe example appears to demonstrate a directional unit that pulls air in through one orifice and then pushes it out another opening. GE must have a reason for showing DCJ units as both round and square, and in many different sizes.
Regardless, like many piezo devices, GE rightly emphasizes that a DCJ would offer an alternative to typical fans that can be thinner, suck less power, and probably can be made just as inexpensively.
But, I must say that it is unclear to me exactly what GE claims the novelty is for its DCJ technology is or what the pedigree on the DCJ patent is. I tried to get more specifics from GE’s press office, but I suspect the holidays have slowed their responses to such inquiries. So, the following are just some random comments.
First, the DCJ is really just a specialized type of piezo pump, and piezo pumps for fluids and gases have been around for years. Piezo pumps also have been around quite a while that use diaphragms and check valves, and they have been available in an array of sizes, too.
A cursory examination of patents seems to indicate that, in particular, a Georgia Tech group was working on the concept of “synthetic jet actuators” in the early and mid 1990s, not just as single units but also in concert with other jet actuators to bend and shape the aggregate jet stream. Northrop Grumman and Lockheed Martin were also tinkering with jet actuators at the time.
One of those working at Lockheed Martin was Seyed Saddoughi, now a principal engineer for GE (interviewed in the above video), and coinventor on patents for several related systems, including a patent for a system and method for “manipulating fluid flow over surface using synthetic pulsators” and pulsed jets. This patent goes on both to describe large- and micro-scale synthetic jets that can optimize fluid flows over aerodynamic surfaces and in gas turbine inlets/outlets, such as for use in advanced aircraft.
Likewise, another group, at GE, as early as 2006 described in a patent filling a piezo “pleumo-jet device” that would be used for thermal management system for embedded electronics.
Regardless, I personally think it would be a breakthrough if these silent DCJ units quickly could find their way into personal electronics: I am often driven to distraction by the strong vibration and the whir of my laptop’s fan when it kicks in and out while I have several processor-intensive applications open. So, GE—best of luck!