Scientists at the John Hopkin’s University have cultivated new sensors for microelectromechanical systems and the devices that are part of the Internet of Things. Although the future of devices that based on IoTs will depend on these kinds of alloy sensors.
Usually, the microelectromechanical systems (MEMS) have internal structures and smaller than the width of a strand of human hair and are shaped out of silicon. In the case of the alloy sensors, they work fine in average temperatures, but even modest amounts of heat. For example, a couple hundred degrees, causes them to lose their strength and their ability to conduct electronic signals. And because the sensors made of silicon, they are very brittle and prone to break.
Materials scientist and mechanical engineer Kevin J. Hemker of Johns Hopkins University’s Whiting School of Engineering said, “For a number of years we’ve been trying to make MEMS out of more complex materials, that are more resistant to damage and better at conducting heat and electricity.”
Although silicon is known as the heart of MEMS technologies for several generations now. But still, it is not ideal for future uses, especially under the high heat and physical stress that future MEMS devices will have to withstand.
Scientists noted, “the pursuit of new materials led them to consider combinations of metal containing nickel and nickel-base superalloys, that generally used to make jet engines.”
By considering the need for dimensional stability, they added the metals molybdenum and tungsten in hopes of curbing the degree pure nickel expands in heat. Scientists then hit targets with ions to vaporize the alloys into atoms and deposit them onto a surface. By doing this, they created a film that can be peeled away. Thus, they were able to create freestanding films with an average thickness of 29 microns i.e., less than the thickness of a human hair.
These freestanding alloy films exhibited extraordinary properties. When pulled, they showed a tensile strength.
Hemker said, “We thought the alloying would help us with strength as well as thermal stability. But we didn’t know it was going to help us as much as it did.”
“The remarkable strength of these alloy sensors is due to atomic-scale patterning of the alloy’s internal crystal structure. The structure strengthens the material and has the advantage of not impeding the material’s ability to conduct electricity.”
During the study, scientists also showed that the films can withstand high temperatures and are both thermally and mechanically stable. Now they are planning for the next step of development. For example, involving shaping the films into MEMS components.