Regensburg 2016 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 52: Focus: Two Dimensional Functional Materials I

CPP 52.4: Talk

Thursday, March 10, 2016, 10:45–11:00, H51

Touchless finger motion tracking with humidity sensitive 1D Photonic Crystals — •Katalin Szendrei — Max Planck Institute for Solid State Research, Stuttgart, Germany — Ludwig Maximilians Universität, München, Germany

1D Photonic Crystals (1D PCs) are periodic multilayered nanostructures exhibiting a photonic band gap - a forbidden spectral range for photons propagating through the nanostructure. These structures are promising candidates for smart optical detectors as the structural color can be dynamically changed by external chemical, physical or biological stimuli. Herein we present 1D PCs fabricated by bottom up assembly from colloidal metal oxide nanoparticles and colloidally stable suspensions of antimony phosphate 2D nanosheets, which show an ultrasensitive response to local humidity changes caused by the moisture induced swelling of the nanosheets. Integrated into a PC, a resulting full spectrum color change is indicative of ultrahigh sensitivity towards water vapor. The combination of a high selectivity, high reproducibility and response time in the subsecond time scale allowed us to detect minute humidity changes. As the human finger is surrounded by a humid atmosphere, finger positions and motions can be tracked and indicated by color changes of the BS in realtime under touchless conditions. These experiments suggest a new device architecture as alternative to the common touchscreen technology. With the touchless technology, the disadvantages of hygienic aspects, mechanical vastage could be avoided, while at the same time the user receives a direct feedback of the finger motion through the optical answer of the display.