Nanophotonic microporous scaffolds are being tested as flexible, bio-friendly devices to monitor biological signals in real-time.

Our bodies are constantly sending signals, alerting us to what we need, but this only helps us if we can decode them quickly enough to react. Wei Zhou envisions a miniature piece of technology that measures the spatiotemporal evolutions in the body's own molecular vibration states or local charge distributions to transmit health information in real-time.

Zhou, an ECE assistant professor, is currently working on a nanoscale photonic device that concentrates and manipulates light with the potential to be integrated into the human body for real-time monitoring of bio-signals.

This technology can be used for healthcare applications, including blood glucose monitoring, which is crucial for diabetes management.

Zhou's research lays the groundwork for the next-generation of bio-integrated nano-systems that incorporate both nanophotonics and nanoelectronics onto the same platform. While other researchers have started to develop such devices for healthcare applications in vitro, Zhou's research targets biomedical applications in vivosuch as implantable nanophotonic biosensors within human tissues.

"Nanoscale photonics within biological systems is a highly unexplored area," said Zhou. "We're working on achieving the humanmachine interface in an elegant and seamless way."

Wei Zhou

The nanophotonic devices can be thought of as nano-lenses or nanoantennas that concentrate light into a nanoscale spot beyond the diffraction limit. When photons of light interact with innate vibration states of biomolecules, the photons will be absorbed or scattered. While most of the scattered photons retain their original energy, a few of them are inelastically affected. Their energy shifts either up or down. This phenomenon, which is called Raman scattering, provides information about the biological signals in the body. Zhou's device takes advantage of these physical properties to enhance the inelastic scattering of the molecule, which provides a real-time biochemical signal in the body.

The next step will involve patching nanoelectric components together with the nanophotonic devices, which could exploit charge-based bio-signals as an additional way to gather health information from the human body in real-time.

"This complementary capability will introduce a much more powerful strategy for interfacing with the biological environment for sensing purposes and signal conversion," said Zhou. The hybridization of photonics and electronics will provide a fail-safe for the measurement in very complicated biological environments, meaning electronics can take over in situations where photonics are faulty, and vice-versa.

To craft this hybrid bio-integrated platform, the members of Zhou's team are challenging themselves to find solutions to problems related to aspects in both biomaterials and device-physics. For starters, the body must not reject the components. Zhou has been testing a flexible microporous substrate as a body-friendly alternative to the harder, more rigid substrates typically used. The device's surface chemistry also needs to recognize the molecule being targeted, glucose for instance, and be able to detect it over a long period of time. And the device must be able to perform in biological fluids without degrading.

The device will be similar enough to biological tissue that the body might not regard it as foreign. Zhou hypothesized that the body may go so far as to adopt the scaffold, growing cells around it. The artificial scaffold incorporated with nano-enabled biosensors then becomes a natural part of the body.