New Worlds: Micro-machines for the human body

Tel Aviv University researchers have adapted microscopic technology for bionic body parts and other medical devices.

Bionic arm 370 (photo credit: REUTERS)
Bionic arm 370
(photo credit: REUTERS)
Decades after the popular bionic science fiction TV character on The Six Million Dollar Man, Tel Aviv University researchers have adapted microscopic technology for bionic body parts and other medical devices.
Tiny sensors and motors are everywhere, telling your smartphone screen to rotate and your camera to focus. But now, the TAU team has found a way to print biocompatible components for these micro-machines, making them ideal for use in bionic arms, for example.
Microelectromechanical systems, better known as MEMS, are usually produced from silicon. Engineering doctoral candidates Leeya Engel and Jenny Shklovsky, under the supervision of Prof. Yosi Shacham-Diamand of the school of electrical engineering, and Slava Krylov of the school of mechanical engineering — are creating a novel micro-printing process that uses a highly flexible and non-toxic organic polymer. The resulting MEMS components can be more comfortably and safely used in the human body, and use less energy.
As their name suggests, MEMS bridge the worlds of electricity and mechanics. They have a variety of applications in consumer electronics, automobiles and medicine. MEMS sensors, like the accelerometer that orients your smartphone screen vertically or horizontally, gather information from their surroundings by converting mechanical or chemical signals into electrical signals. MEMS actuators, which may focus your next smartphone’s camera, work in the other direction – executing commands by converting electrical signals into movement. Both types of MEMS depend on micro- and nano-sized components, such as membranes, either to measure or produce the necessary movement.
For years, MEMS membranes, like other MEMS components, were primarily fabricated from silicon using a set of processes borrowed from the semiconductor industry. TAU’s new printing process, published in the journal Microelectronic Engineering and presented at the recent AVS 59th International Symposium in Tampa, Florida, yields rubbery, paper-thin membranes made of a particular kind of organic polymer. This material has specific properties that make it attractive for micro- and nano-scale sensors and actuators. More importantly, the polymer membranes are more suitable for implantation in the human body than their silicon counterparts, which partially stems from the fact that they are hundreds of times more flexible.
The unique properties of the polymer membranes have unlocked unprecedented possibilities. Their flexibility could help make MEMS sensors more sensitive and MEMS motors more energy efficient. They could be key to better cameras and smartphones with a longer battery life, the researchers said.
But the printing process may bring the biggest benefit to the field of medicine, where polymer membranes could be used in diagnostic tests and smart prosthetics. There are already bionic limbs that can respond to stimuli from an amputee’s nervous system and the external environment, and prosthetic bladders that regulate urination for people paralyzed below the waist. Switching to MEMS made with the polymer membranes could help make such prosthetics more comfortable, efficient and safer for use on or inside the body.
“The use of new, soft materials in micro devices stretches both the imagination and the limits of technology,” Engel said, “but introducing polymer MEMS to industry can be realized only with the development of printing technologies that allow for low-cost mass production.”
The team’s new polymer membranes can already be produced quickly and inexpensively. The polymer base for the membranes was supplied along with a grant by French chemical company Arkema/Piezotech.
“They just gave us the material and asked us to see what devices we could create with it,” Engel recalled. “This field is like Legos for grownups.” The next step is to use the printing process to make functional sensors and actuators almost entirely out of the polymer at the micro- and nano-scales. Such flexible machines could be put to use in things like artificial muscles and screens so flexible that you can roll them up and put them in your pocket.
DOGGED BY YAWNING If you’re a dog owner, you may be certain there there is a strong emotional bond between you and your pooch. This may be illustrated by when and how a dog yawns, according to University of Tokyo research just published in the open-access journal PLoS One.
Dogs yawn when they see a person yawning and respond more frequently to their own owner’s yawns than to a stranger’s, according to researcher Teresa Romero and colleagues.
Pet dogs in the study watched their owner or a stranger yawn or fake a yawn. But they yawned significantly more in response to their owners’ actions than to the strangers. The dogs also responded less frequently to the fake movements, suggesting they have the ability to yawn contagiously when they see the real thing.
Previous research has shown that dogs yawn in response to human yawns, but it was unclear whether this was a mild stress response or an empathetic response. The results of this study suggest the latter, as dogs responded more to their owners’ genuine yawns than those of a stranger.
The researchers observed no significant differences in the dogs’ heartbeat during the experiments, making it unlikely that their yawns were a distress response.
Explaining the significance of the results, Romero says, “Our study suggests that contagious yawning in dogs is emotionally connected in a way similar to humans. Although our study cannot determine the exact underlying mechanism operative in dogs, the subjects’ physiological measures taken during the study allowed us to counter the alternative hypothesis of yawning as a distress response.