Upconverting Nanoparticles as Optical Sensors of Nano- to Micro-Newton Forces
[1];
[3];
- Stanford Univ., CA (United States). Dept. of Applied Physics
- Stanford Univ., CA (United States). Dept. of Materials Science and Engineering
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
- Stanford Univ., CA (United States). Dept. of Molecular and Cellular Physiology
- Stanford Univ., CA (United States). Dept. of Geological Sciences
Mechanical forces affect a myriad of processes, from bone growth to material fracture to touch-responsive robotics. While nano- to micro-Newton forces are prevalent at the microscopic scale, few methods have the nanoscopic size and signal stability to measure them in vivo or in situ. Here, we develop an optical force-sensing platform based on sub-25 nm NaYF4 nanoparticles (NPs) doped with Yb3+, Er3+, and Mn2+. The lanthanides Yb3+ and Er3+ enable both photoluminescence and upconversion, while the energetically coupled d-metal Mn2+ adds force tunability through its crystal field sensitivity. Using a diamond anvil cell to exert up to 3.5 GPa pressure or ~10 μN force per particle, we track stress-induced spectral responses. The red (660 nm) to green (520, 540 nm) emission ratio varies linearly with pressure, yielding an observed color change from orange to red for α-NaYF4 and from yellow–green to green for d-metal optimized β-NaYF4 when illuminated in the near infrared. Consistent readouts are recorded over multiple pressure cycles and hours of illumination. With the nanoscopic size, a dynamic range of 100 nN to 10 μN, and photostability, these nanoparticles lay the foundation for visualizing dynamic mechanical processes, such as stress propagation in materials and force signaling in organisms.
- Research Organization:
- Energy Frontier Research Centers (EFRC) (United States). Light-Material Interactions in Energy Conversion (LMI); SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Argonne National Laboratory (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE National Nuclear Security Administration (NNSA); National Science Foundation (NSF)
- Grant/Contract Number:
- FG02-99ER45775; SC0001293; 2013156180; AC02-06CH11357; AC02-76SF00515; NA0001974
- OSTI ID:
- 1390327
- Alternate ID(s):
- OSTI ID: 1440363
- Journal Information:
- Nano Letters, Vol. 17, Issue 7; ISSN 1530-6984
- Publisher:
- American Chemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
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