Organic molecule based sensor for aldehyde detection

Abstract

Aldehydes are used in food and beverage industries, production of resins, soap and perfume industries. When used in excess quantity or found in products in undesired quantity this is a threat to humans. Hence it becomes very important to detect these VOCs even at lower concentration. The other sources of aldehyde are polluted air and water. Exposure to aldehyde can cause gene mutation and cancer. Conductometric sensors with metal oxide semiconductors as sensing films, cataluminesence based sensors, quartz crystal microbalance sensors, analytical methods such as HPLC have been used for the detection of aldehydes. These are sophisticated techniques require skilled staff to perform the tests. Chemiresistor is a simple method of fabrication of conductometric sensor. In this method the sensing layer is a film cast between two electrodes deposited on an insulating substrate. The response of the sensor to various analytes is monitored by recording the changes taking place in the sensing element. Organic molecule based sensors are low cost and operate at room temperature. Selectivity of the sensors to a particular analyte is an issue in sensors. An analyte molecule can interact with the various binding sites on a molecule. A molecule has to be designed and synthesized to be selective to a particular analyte of interest. This can be achieved by selecting a molecule which has a functional group that interacts with the analyte molecule. The mechanism of interaction of the analyte with the sensing molecule can be understood by doing molecular simulations. Molecular modelling allows monitoring the interaction of the analyte and sensing molecule. Here an example of organic molecule based sensor for selective interaction with aldehydes is illustrated. The organic molecule o- phenylenediamine blended with carbon black as sensing element of the chemiresistor to decrease the resistance. Molecular modelling can be used to understand the interaction between aldehyde and o-phenylenediamine molecule.