<p>The humble Scotch tape - a versatile household staple - may find a new scientific application as a shape-changing “smart material”.<br /><br /></p>.<p>Researchers used a laser to form slender half centimetre long fingers out of the tape. When exposed to water, the four wispy fingers morph into a tiny robotic claw that captures water droplets.<br /><br />The innovation could be used to collect water samples for environmental testing, said Babak Ziaie, a Purdue University professor of electrical and computer engineering.<br />The Scotch tape - made from a cellulose-acetate sheet and an adhesive - is uniquely suited for the purpose.<br /><br />“It can be micro-machined into different shapes and works as an inexpensive smart material that interacts with its environment to perform specific functions,” Ziaie said.<br /><br />Researcher Manuel Ochoa came up with the idea. While using tape to collect pollen, he noticed that it curled when exposed to humidity. The cellulose-acetate absorbs water, but the adhesive film repels water.<br /><br />“So, when one side absorbs water it expands, the other side stays the same, causing it to curl,” Ziaie said.<br /><br />A laser was used to machine the tape to a tenth of its original thickness, enhancing this curling action. The researchers coated the graspers with magnetic nanoparticles so that they could be collected with a magnet.<br /><br />“Say you were sampling for certain bacteria in water. You could drop a bunch of these and then come the next day and collect them,” Ziaie said in a statement.<br /><br />The grippers close underwater within minutes and can sample one-tenth of a millilitre of liquid. “Although brittle when dry, the material becomes flexible when immersed in water and is restored to its original shape upon drying, a crucial requirement for an actuator material because you can use it over and over,” Ziaie said.<br /><br />“Various micro-structures can be carved out of the tape by using laser machining. This fabrication method offers the capabilities of rapid prototyping and batch processing without the need for complex clean-room processes,” he said.</p>
<p>The humble Scotch tape - a versatile household staple - may find a new scientific application as a shape-changing “smart material”.<br /><br /></p>.<p>Researchers used a laser to form slender half centimetre long fingers out of the tape. When exposed to water, the four wispy fingers morph into a tiny robotic claw that captures water droplets.<br /><br />The innovation could be used to collect water samples for environmental testing, said Babak Ziaie, a Purdue University professor of electrical and computer engineering.<br />The Scotch tape - made from a cellulose-acetate sheet and an adhesive - is uniquely suited for the purpose.<br /><br />“It can be micro-machined into different shapes and works as an inexpensive smart material that interacts with its environment to perform specific functions,” Ziaie said.<br /><br />Researcher Manuel Ochoa came up with the idea. While using tape to collect pollen, he noticed that it curled when exposed to humidity. The cellulose-acetate absorbs water, but the adhesive film repels water.<br /><br />“So, when one side absorbs water it expands, the other side stays the same, causing it to curl,” Ziaie said.<br /><br />A laser was used to machine the tape to a tenth of its original thickness, enhancing this curling action. The researchers coated the graspers with magnetic nanoparticles so that they could be collected with a magnet.<br /><br />“Say you were sampling for certain bacteria in water. You could drop a bunch of these and then come the next day and collect them,” Ziaie said in a statement.<br /><br />The grippers close underwater within minutes and can sample one-tenth of a millilitre of liquid. “Although brittle when dry, the material becomes flexible when immersed in water and is restored to its original shape upon drying, a crucial requirement for an actuator material because you can use it over and over,” Ziaie said.<br /><br />“Various micro-structures can be carved out of the tape by using laser machining. This fabrication method offers the capabilities of rapid prototyping and batch processing without the need for complex clean-room processes,” he said.</p>