A fourteen-year-old has won the 3M Young Scientist Challenge. Sirish Subash created a device called Pestiscand. It is a handheld device for at-home use to detect pesticide residue on produce without damaging the food. It measures the wavelength of light reflecting off of fruits and vegetables and uses a machine-learning model to analyse the data. Users download a phone app, point Pestiscand at the produce, tap the scan button and voilà, they see if their apple or spinach needs another rinse.