Microplastics are found even in mountain glaciers and food. Conventional spectroscopy, analysis by light, required expensive detectors for invisible infrared radiation. The new method sidesteps that: the device creates a pair of light twins. One twin (infrared) makes plastic molecules, chains of carbon and hydrogen, vibrate like guitar strings. The second (visible) reads those vibrations and passes the picture to an ordinary camera — the kind in every smartphone. By tracking changes in signal brightness, the detector instantly distinguishes plastic from a wrapper or bottle. The fist-sized gadget delivers 100 measurements per second without nitrogen cooling or bulky lasers. Soon, pocket analyzers will test stream water right on the spot.