Foldable and Cytocompatible Sol-gel TiO2 Photonics.
Integrated photonics provides a miniaturized and potentially implantable platform to manipulate and enhance the interactions between light and biological molecules or tissues in in-vitro and in-vivo settings, and is thus being increasingly adopted in a wide cross-section of biomedical applications ranging from disease diagnosis to optogenetic neuromodulation. However, the mechanical rigidity of substrates traditionally used for photonic integration is fundamentally incompatible with soft biological tissues. Cytotoxicity of materials and chemicals used in photonic device processing imposes another constraint towards these biophotonic applications. Here we present thin film TiO2 as a viable material for biocompatible and flexible integrated photonics. Amorphous TiO2 films were deposited using a low temperature (<250 °C) sol-gel process fully compatible with monolithic integration on plastic substrates. High-index-contrast flexible optical waveguides and resonators were fabricated using the sol-gel TiO2 material, and resonator quality factors up to 20,000 were measured. Following a multi-neutral-axis mechanical design, these devices exhibit remarkable mechanical flexibility, and can sustain repeated folding without compromising their optical performance. Finally, we validated the low cytotoxicity of the sol-gel TiO2 devices through in-vitro cell culture tests. These results demonstrate the potential of sol-gel TiO2 as a promising material platform for novel biophotonic devices.
University of Delaware, Department of Materials Science &Engineering, Newark, Delaware 19716, USA.
Lan
L
Li
Tianjin University, School of Electronic and Information Engineering, Tianjin 300072, China.
Ping
P
Zhang
University of Hawaii at Manoa, Department of Mechanical Engineering, Honolulu, Hawaii 96822, USA.
Wei-Ming
WM
Wang
University of Delaware, Department of Materials Science &Engineering, Newark, Delaware 19716, USA.
Hongtao
H
Lin
University of Delaware, Biomedical Engineering Program, Newark, Delaware 19716, USA.
Aidan B
AB
Zerdoum
University of Delaware, Department of Materials Science &Engineering, Newark, Delaware 19716, USA.
Sarah J
SJ
Geiger
University of Delaware, Department of Materials Science &Engineering, Newark, Delaware 19716, USA.
Yangchen
Y
Liu
University of Delaware, Department of Materials Science &Engineering, Newark, Delaware 19716, USA.
Nicholas
N
Xiao
University of Delaware, Department of Materials Science &Engineering, Newark, Delaware 19716, USA.
Yi
Y
Zou
University of Delaware, Department of Materials Science &Engineering, Newark, Delaware 19716, USA.
Okechukwu
O
Ogbuu
University of Delaware, Department of Materials Science &Engineering, Newark, Delaware 19716, USA.
Qingyang
Q
Du
University of Delaware, Department of Materials Science &Engineering, Newark, Delaware 19716, USA.|University of Delaware, Biomedical Engineering Program, Newark, Delaware 19716, USA.
Xinqiao
X
Jia
University of Hawaii at Manoa, Department of Mechanical Engineering, Honolulu, Hawaii 96822, USA.
Jingjing
J
Li
University of Delaware, Department of Materials Science &Engineering, Newark, Delaware 19716, USA.|Massachusetts Institute of Technology, Department of Materials Science &Engineering, Cambridge, Massachusetts 02139, USA.
Juejun
J
Hu
D008962:Models, Theoretical; D055095:Optics and Photonics / Q000295:instrumentation* / Q000379:methods*; D014025:Titanium
C009495:titanium dioxide; D014025:Titanium