A piece of polypropylene was ground using 2000-grit sandpaper. The plastic particles were suspended in 10 mL of water, and 1 mL of this suspension was flown inside the microfluidic device. The water was pushed out, and a 2 mg/L solution of nile red in acetone was flowed in. The acetone solution was left in the channel for 20 secs before being pushed out with airflow from an empty syringe. The fluorescent micrograph was recorded on a Leica DMi8 using a rhodamine filter set (ex:541-551 em:565-605).