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A team of electrical and mechanical engineers at Israel’s Tel Aviv University (TAU) has developed a way to print biocompatible components for microelectromechanical systems (MEMS), making them ideal for use in medical devices, like bionic prosthetic arms. MEMS are usually fabricated from silicon using processes borrowed from the semiconductor industry. But, the unique innovation of the TAU researchers is creating a novel micro-printing process that works using a highly flexible, non-toxic organic polymer. The resulting MEMS components, they say, can be more comfortably and safely used in the human body, as well as expend less energy.

MEMS sensors, like the accelerometer that orients your smartphone screen vertically or horizontally, gather information from their surroundings by converting movement or chemical signals into electrical signals. MEMS actuators, which may 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, either to measure or produce the necessary movement.

TAU's new printing process yields very flexible, paper-thin membranes made of a particular kind of organic polymer with specific properties that make it attractive for micro- and nano-scale sensors and actuators. Their flexibility could help make MEMS sensors more sensitive and MEMS motors more energy efficient.

The engineers say that the polymer membranes could be used in devices such as 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 next step, they say, 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 flexible screens that can be rolled up and carried in a pocket.

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