Who knew 2007 would be such a boom year for prosthetic ankles? Surely not us, but what a year it's been, with MIT's artificial foot and ankle design we saw last month, and the ankle exoskeleton we saw the University of Michigan working on in February. Today's "ankle flavor of the week" comes to us from Arizona State University, where some doctoral students have created "SPARKy," which they expect to "revolutionize prosthetics" and plan for it to be "especially helpful for military personnel wounded in active duty." SPARKy stands for "Spring Ankle with Regenerative Kinetics," and is meant to allow amputees a more traditional walk, instead of having to compensate with other muscles and work 20 to 30 percent harder to get where they're going. The concept is pretty straight forward: "What we hope to create is a robotic tendon that actively stretches springs when the ankle rolls over the foot, thus allowing the springs to thrust or propel the artificial foot forward for the next step." There's a lightweight motor involved, but apparently this method is much less obtrusive than other such projects, which use large motors or high pressure. The robotic tendon should be ready for its first phase of demonstration in December of this year.