Gas sensing with porphyrin monolayers

At imec, ULP Sensors

Introduction

Porphyrins are macrocyclic molecules which can accomodate a metal ion in their center, and which can be found throughout nature. For example, magnesium-containing porphyrins (chlorophylls) are involved in photosynthesis in green plants, and iron-containing porphyrins (hemes, see figure below) transport oxygen in blood. This last example already shows that metalloporphyrins have a strong affinity to certain gas molecules. This has triggered interest in the application of porphyrins for gas sensing. At Holst Centre, the gas binding properties of self-assembled monolayers of porphyrins are investigated. It has been shown that monolayers of porphyrins such as the one shown below can be assembled on oxide surfaces. Binding of gas molecules to the surface-bound porphyrins leads to changes in the electrical properties of the surface. Therefore, porphyrin monolayers are very promising for application in the gas sensors which are also being developed at Holst Centre.

Project description

Experiments have been done with the porphyrin shown above (with different metal ions), and the response to NO has been measured under laboratory conditions. However, many things still need to be investigated, including:

• response under realistic conditions (e.g. ambient humidity and oxygen levels);
• response and cross-sensitivity to different gases;
• deposition of porphyrins on real sensors and measurement of the gas response.

Activities could include:

• preparation and characterization of porphyrin monolayers;
• measurement of gas response by Kelvin probe;
• measurement of gas response with real sensors.
  

Requirements

• We are looking for a motivated MSc-student with a background in chemistry or physics;
• Good English communication skills.

For all inquiries, please contact:

Ms Sandra Maas, Management Assistant Human Resources.
Telephone number: +31 (0)40 40 20 500.

Application form