APPLICATIONS OF TECHNOLOGY:
- Detecting incipient cracks in structural nanocomposites
- Monitoring stresses in biological tissues
- Other nanoscale tensile / compressive stress sensing applications
- Applicable to many materials
- Instant local stress reporting
- Excellent cyclability
- No degradation of the host polymer
Nanoscale stress sensing can be used across fields ranging from detection of incipient cracks in structural mechanics to monitoring forces in biological tissues. We demonstrate how tetrapod quantum dots (tQDs) embedded in block copolymers act as sensors of tensile / compressive stress. tQDs can detect their own composite dispersion and mechanical properties with a switch in optomechanical response when tQDs are in direct contact.
Using experimental characterizations, atomistic simulations, and finite-element analyses, a team of Berkeley Lab scientists led by Paul Alivisatos and Robert Ritchie show that under tensile stress, densely packed tQDs exhibit a photoluminescence peak shifted to higher energies (blue-shift) due to volumetric compressive stress in their core; loosely packed tQDs exhibit a peak shifted to lower energies (red-shift) from tensile stress in the core. The stress shifts result from the tQDs unique branched morphology in which the CdS arms act as antennas that amplify the stress in the CdSe core. The Berkeley Lab nanocomposites exhibit excellent cyclability and scalability with no degraded properties of the host polymer. Colloidal tQDs allow sensing in many materials to potentially enable autoresponsive, smart structural nanocomposites that self-predict impending fracture.
DEVELOPMENT STAGE: Proven principle
FOR MORE INFORMATION:
Shilpa, N., Zherebetskyy, D., Wu, S., Ercius, P., Powers, A., Olson, A., Du, D., Lin, L., Govindjee, S., Wang, L-W, Xu, T., Alivisatos, P., Ritchie, R. “Mechanisms of Local Stress Sensing in Multifunctional Polymer Films Using Fluorescent Tetrapod Nanocrystals,” NanoLetters 16, 2016, 5060-5067.
STATUS: Published U.S. Patent Application 15/607,158 (Publication 2018/0045590). Available for licensing or collaborative research.
SEE THESE OTHER BERKELEY LAB TECHNOLOGIES IN THIS FIELD:
Luminescent Nanocrystal Stress Gauge, JIB-2727
Branched 3-D Inorganic Nanocrystals for Biological Imaging and Electronics Applications, IB-1773