Extremely Sensitive Mechanochromic Materials Capable of Distinguishing Cancer Cells Having Different Cellular Traction Forces

ABSTRACT The detection of biologically relevant subtle mechanical forces, such as cellular traction forces (CTFs, ∼kPa), is critical for advancing cancer diagnostics and understanding mechanobiology. However, conventional mechanochromic molecules require high mechanochromic threshold stresses (∼GPa) for their fluorescence changes, restricting their applicability in biomedical applications. Here, we present an innovative class of mechanochromic molecules showing unprecedented mechanochromic threshold stress of 0.5 Pa. The mechanochromic molecules undergo a supercooled liquid‐to‐crystal transition with clear fluorescence deviation upon mechanical stimuli, while showing gradually controlled mechanochromic sensitivity. Our extremely sensitive mechanochromic devices effectively distinguish cancer cells having different CTF characteristics, correlating with their metastatic tendencies. Especially, patient‐derived cancer cells from primary tumors and metastatic sites exhibited distinct contrasts in fluorescence signal turn‐on rates of 18.7% and 73.5%, respectively, emphasizing this platform's potential for cancer diagnostics and therapeutic monitoring. This work represents a significant advance in mechanochromic materials technology, providing high‐sensitivity tools for various biomedical applications.