Peng Jiang

Abstract:

Here we report novel chromogenic sensors that exhibit easily perceived color changes when exposed to different external stimuli, such as pressure, shear stress, ballistic impact, a large variety of vapors and liquids, heat, and acoustic wave. These multifunctional sensors are reusable, inexpensive, light weight, consuming no electrical power, and very small footprint, promising for a spectrum of applications ranging from user-friendly environmental monitoring to specifically sensing chemicals. This new technology is enabled by integrating scientific principles drawn from two disparate fields that do not typically intersect  the fast-growing photonic crystal and shape memory polymer (SMP) technologies. The active components of the SMPs are thin macroporous photonic crystal layers (only a few m thick) which are fabricated by using self-assembled, 3-D highly ordered colloidal crystals as structural templates. This microscopic thin-film configuration renders orders of magnitude faster response speed than bulky SMP samples in traditional applications. In addition, by leveraging easily perceived color changes associated with the unconventional all-room-temperature shape memory cycles enabled by the recent discovery of a new series of multi-stimuli-responsive SMPs, sensitive and specific detection of an analyte in a multicomponent solution, such as ethanol in gasoline with a detection limit of 10 ppm, has been demonstrated. Moreover, we have demonstrated the sensitive detection of a trace amount of benzene-toluene-xylene (BTX) in contaminated water using these novel chromogenic sensors. Furthermore, our approach provides a simple and sensitive optical technique for investigating the intriguing shape memory effects at nanoscale, which is a topic that has received little examination.