Sensors enable us to monitor changes in systems of all kinds.
The materials at the heart of those sensors, of course, ultimately determine their end-use application. Devices made of silicon, for example, enable ultrafast processing in computers and phones, but they aren’t pliable enough for use in physiological monitoring.
They also require a lot of energy to produce.
Elsa Reichmanis, Carl Robert Anderson Chair in the Department of Chemical and Biomolecular Engineering, recently received a grant from the National Science Foundation for her proposal to identify new materials platforms that could form the basis of effective sensors for applications in areas like physiological, environmental, and Internet of Things monitoring, while increasing the energy efficiency of fabrication processes.
“We’ll be creating the polymers that could be the building blocks of future sensors,” says Reichmanis, who is the lead researcher on the project, which also includes Thomas Gartner, an assistant professor of chemical and biomolecular engineering. “The systems we’re looking at have the ability to interact with ions and transport ionic charges, and in the right environment, conduct electronic charges.”
Having the ionic charge within the organized polymer network can essentially “dope” the charge of the polymer so that it becomes a semiconductor.
“And then as a semiconductor with very low applied voltages,” she says, “there will be charge transport, which can then lead to an electronic signal readout that can tell you what's happening.”
The network will also be functionalized to interact with various species, she says. Taken together, functionalized material that can act as a semiconductor could be used in a range of applications.
“They could be used in biomedical sensors to react to different bacteria or a virus or changes in metabolites,” she says. “Environmental sensors could be used in atmospheric monitoring to detect various pollutants and where they are, and in what concentrations. And for Internet of Things applications, these sensors could allow workstations to feed information using wireless signaling.”
Specifically, Reichmanis, Gartner, and their team will explore what kinds of polymers and functionalities will support organic mixed ion electron conduction, where both ions and electrons get transported. That ability to support the transport of both allows for a better signal-to-noise ratio, which enables the user to determine if something is, indeed, really there. It also allows for devices to operate at low voltage—an especially important characteristic when considering their use on or in the human body.
“We’ll be researching the chemistries involved, but then simultaneously, from a modeling simulation perspective, how are these ions actually interacting with the polymers and their functionalities on a more fundamental level? What is the interaction between ion transport and electron transport?”
Ultimately, she says, the goal is to broaden the choice of building block materials, expand the functionalities that support mixed conduction, and come to a better understanding of what mixed conduction is really about.
“We have the opportunity to develop something within a real area of need,” says Reichmanis, “and because these devices are so wide-ranging, it opens up opportunities for much broader collaborations.”
