Young Researcher - Sorting Plastics with IR Technology

28 Feb 2018

Using components provided by LASER COMPONENTS, a smart student from Lower

Saxony developed a method for sorting plastics that could have an effect on the

recycling industry. For his project in “Schüler experimentieren” – a popular science

competition for German pupils under 15 – Felix Meyer, a student of Osterholz-

Scharmbeck Integrated High School, used six IR diodes to distinguish different

kinds of plastics. For a sensor, he used an extended InGaAs photodiode (IG22X-

500S4i) provided by the manufacturer LASER COMPONENTS, from

Olching near Munich.

Each kind of plastic absorbs different wavelengths in the infrared spectrum. For

almost twenty years, sorting plants have been using spectrometers to determine

which piece of plastic is made from which material. To do so, the objects are irradiated

with a mixture of many diff erent wavelengths and the entire reflected light

is analysed using several costly IR spectroscopes. The method developed by Felix

is similarly effective, but considerably cheaper: it is limited to six clearly defined

IR wavelengths and measures the intensity of reflected radiation. This results in a

spectrum of interpolation points characterising each plastic.

Felix could clearly distinguish eight commonly used types of plastic with his

experimental scanner. Meanwhile, his project has earned several awards and the

student has even applied for a patent.

“When Felix asked us for a photodiode, we didn’t have to think twice before sending

him a free sample”, says Uwe Asmus, product engineer for IR components.

“We are quite impressed that his science project deals with such complex topics.”

More Information https://www.lasercomponents.com/uk/product/ingaas-500-2600-nm-1/