Low-cost on -site dioxin sensor in epitaxial graphene on SiC

Important results from the project

Dioxins are a group of extremely toxic and difficult to degrade substances that are formed during incomplete combustion, e.g. in Combined Heat and Power plants. This project aimed at developing a portable sensor for on-site analysis of dioxins. This is challenging as dioxins are toxic at very low concentrations, but the high sensitivity of epitaxial graphene makes it possible. The project reached proof-of-concept of a portable instrument for dioxin detection using tailor-made pre concentrators. However, demonstration of selective detection in a complex matrix is still missing.

Expected long term effects

We have developed a sensor solution with a chip cost of cirka 200 SEK that allows determination of dioxin concentrations within 45 minutes. Compared to today’s methods, with costs per sample between 5000 and 15000 SEK, need for expensive equipment and 3 - 5 days of work for skilled lab technicians, our solution seems very promising. Moreover, a more cost/resource-effective determination of dioxins is expected to result in new markets opening due to the elimination of economic and practical obstacles.

Approach and implementation

A Zr-based metal-organic-framework was used as pre-concentrator for dioxins, and temperature programmed desorption (TPD) for selecting the analyte of interest (from a complex matrix) to be transported to ultra-sensitive graphene-based sensors. To establish the TPD protocol, we studied the desorption vs. temperature characteristics of tcdd (in water) that had been accumulated in the Zr-MOF. Based on mass spectrometry, a measurement protocol was established for pre-concentration, evaporation of water, and temperature ramping for desorption and detection of tcdd.