Technology to improve plastics sorting using thermal barcodes
Last update on Jul 24, 2026
Barcode readers identify groceries and other retail products in an instant. Applying that same logic to industrial recycling lines could make plastics sorting faster and more cost-effective, according to a research team at the University at Buffalo (UB).
Rather than relying on optical sensors, the UB team is developing a system built on "three-dimensional transient thermal barcodes" that can identify plastics as they move along conveyor belts. Formulators, recyclers, and material recovery facility operators evaluating faster sorting methods can look to this early-stage technique as a potential alternative to optical scanning.
Manual sorting results in false identification
"Our goal was to develop a cost-effective, scalable and industrially relevant plastics sorting technique that addresses the key prevailing scientific gaps restricting the recycling of plastics," says corresponding author Amit Goyal, SUNY Distinguished Professor and SUNY Empire Innovation professor in UB’s Department of Chemical and Biological Engineering.
Goyal directs the UB Initiative on Plastics Recycling and Innovation, designated as a New York State Center for Plastics Recycling Research and Innovation by the New York State Department of Environmental Conservation (DEC).
According to Goyal, the system aims to "improve the quality of sorted plastics by reducing contamination and, hence, increasing the recycling of these materials to help enable a circular economy." He adds that "it is estimated that one ton of recycled plastic saves 5.7 megawatts of electricity, 685 gallons of oil, and 30 cubic yards of landfill space."
Recyclers and sorters can trace part of today’s low global plastic recycling rates to persistent gaps in identification technology. Plastic waste from households and businesses arrives at material recovery facilities, where it is separated from other waste streams, often by hand. Manual sorting can result in false identification and poor-quality sorted bales.
Plastics are then separated into different resin types. At present, formulators and recyclers lack a cost-competitive and accurate technique for identifying plastic types by resin code. Existing methods, including near-infrared spectroscopy, Raman spectroscopy, and laser-induced breakdown spectroscopy, each carry one or more limitations: poor sensitivity, subpar selectivity, slow speeds, an inability to detect black plastics, or a lack of standoff-mode operation (identifying plastics from a distance), which material recovery facilities often require.
A molecular fingerprint approach to identification
To address these gaps, the UB team set out to develop a technology that captures the molecular signature of waste plastics from a distance and that could be retrofitted into existing sorting machinery.
The researchers use a range of mid-infrared wavelengths, shone directly onto plastic items. Mid-infrared is known as the "molecular fingerprint regime" because it contains unique spectral peaks for every plastic type. As a plastic absorbs the light, its molecular bonds vibrate, generating temporary heat patterns that a thermal camera measures. These heat patterns reflect the unique molecular structure of each plastic, forming what the researchers describe as a "three-dimensional thermal barcode."
Image credits: University at Buffalo