August 8, 2013
New ‘Micro-Printing’ Process Could Improve Prosthetics And Other Medical Devices
redOrbit Staff & Wire Reports - Your Universe Online
A team of researchers at Tel Aviv University (TAU) has developed a way to print biocompatible micro-machines - tiny sensors and motors - that could lead to improvements in medical devices like bionic arms.
Such tiny micro-electromechanical systems, or MEMS, are already in widespread use today in a variety of applications from consumer electronics to automobiles and medicine.
These conventional MEMS are typically produced from silicon, but the TAU researchers created a novel micro-printing process that works with a highly flexible and non-toxic organic polymer, resulting in MEMS components that expend less energy and can be more comfortably and safely used in the human body.
As their name suggests, MEMS bridge the worlds of electricity and mechanics. MEMS sensors, such as the accelerometer that orients a smartphone screen vertically or horizontally, gather information from their surroundings by converting movement or chemical signals into electrical signals. MEMS actuators, such as those that focus a 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, to either measure or produce the necessary movement.
For years, MEMS membranes were mainly fabricated from silicon using a set of processes borrowed from the semiconductor industry. But TAU's new printing process produces 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. Moreover, the polymer membranes are better suited for implantation in the human body than their silicon counterparts, in part because they are hundreds of times more flexible than conventional materials.
The researchers say these unique properties have unprecedented possibilities to help improve the sensitivity of MEMS sensors and the energy efficiency of MEMS motors. They could, for instance, be the key to better cameras and smartphones with a longer battery life.
But the new micro-printing process may deliver the biggest boost to the field of medicine, where polymer membranes could be used in devices like diagnostic tests and smart prosthetics.
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, are already in use today. However, switching to MEMS made with the polymer membranes could make these prosthetics even more comfortable, efficient and safer for use on or inside the body, the researchers said.
"The use of new, soft materials in micro devices stretches both the imagination and the limits of technology," said TAU engineering doctoral candidate Leeya Engel, one of the researchers on the project.
"Introducing polymer MEMS to industry can only be realized with the development of printing technologies that allow for low cost mass production."
The polymer base for the membranes was supplied by French chemical producer Arkema/Piezotech.
"They just gave us the material and asked us to see what devices we could create with it," Engel said. "This field is like Legos for grownups."
The researchers now plan to use their printing process to make functional sensors and actuators almost entirely out of the polymer at the micro- and nano-scales. Such flexible machines could ultimately be used in things like artificial muscles and screens that are flexible enough to roll up and place in a pocket.
A report about the TAU micro-printing process is published in the journal Microelectronic Engineering, and the work was presented at the AVS 59th International Symposium in Tampa, FL.