CHE Seminars  


Speaker Dr. Prabhakar Rai
Department of Materials Science and Engineering, Korea University, South Korea
Topic Fabrication of Highly Sensitive and Selective Metal Oxide Semiconductor Gas Sensors: Exhaled breath analysis and disease diagnosis
Date 18 ,September 2014 (Thursday) 2014
Place L8
Time 4.00 PM - 5.00 PM


Gas sensors are a crucial part of modern life with applications in environmental monitoring, domestic safety, public security and food quality assessment amongst many others. Sensors are increasingly being integrated into mass-market applications, for instance in air quality control in buildings and motor vehicles, as well as the more traditional areas of toxic and explosive gas detection. The market for gas sensors is currently worth ┐630 annually with new applications driving innovation, for instance the analysis of gases from the gut and breath for non-invasive diagnosis of disease. Therefore, the aim of this proposal is to develop nanostructured metal oxide semiconductor (SnO2, ZnO, WO3, CuO, NiO etc.) materials to produce highly sensitive, highly selective sensor devices for application in specific sensing regimes. Poor selectivity is the basic problem of metal oxide gas sensor but modification with metal ┐catalyst┐ particles or use of combinations of sensors with different properties, i.e. n-type and p-type, can help overcome this barrier. Also, the use of nanomaterials has been shown to allow gas sensors to work at lower temperature, with better sensitivity, selectivity and long term stability than sensors based on bulk materials. However, the ability to easily fabricate nanomaterial based gas sensors using an industrially relevant technique is currently not achievable under the state-of-the-art. This project addresses this by exploring a low cost readily-industrialised pulse electrophoresis deposition (PED) method, in which nanostructured n-type metal oxides (ZnO, SnO2, In2O3 and WO3), p-type metal oxides (Cu2O, CuO, NiO), and their hetrostructures with noble metals (Au, Pt or Pd) will be synthesized by wet-chemical methods and then integrated with a sensor substrate using PED. Another aim of this proposal is to apply these gas sensors in exhaled-breath analysis for diagnosis of diseases. Human breath is composed of a hundreds of volatile organic compounds (VOCs) and an accurate detection of specific VOCs in exhaled breath, known as biomarkers, can provide essential information for the diagnosis of those diseases. The compounds of interest are generally to be found at 1-20 parts per billion (ppb) in healthy human breath but can be increased 10-100-fold in the breath of sick patients. For example, the exhaled toluene level in lung cancer patients is known to be approximately 80┐100 ppb, which is two or three-fold higher than the level exhaled by healthy people (20┐30 ppb). Therefore, development of a toluene sensor can help in early detection of lung cancer. This project will contribute to advances in the design and construction of new components, devices and systems allowing improvements in quality of life, safety, security and efficiency in industrial processes.


Dr. Prabhakar Rai obtained his Bachelor of Science degree from D.D.U. Gorakhpur University (2002) and Master of Science degree in Inorganic Chemistry in 2006 at University of Allahabad, India. He received his Doctoral degree in Informatic Electronics Materials Engineering in 2012 at Chonbuk National University, South Korea. He was appointed as an Adjunct Assistant Professor, a Postdoctoral Fellow and an Assistant Research Professor at Chonbuk National University from March 2012 to September 2013. He moved to Korea University in 2013 as a Research Professor in Materials Science and Engineering department. Recently, he has been selected for DST-INSPIRE Faculty Award 2014. His research is mainly focused on synthesis of nanoscale metals and metal oxides for gas sensor applications. This research has led to 35 publications and over 30 presentations at international and national conferences. He received best oral presentation award at International Conference on Nano Science & Engineering Application (ICONSEA-2014) India and best poster award at Korean Sensor Society Conference 2011, South Korea. He has worked as Technical Program Committee member at International Conference on Material Science and Engineering (ICMSE 2014), India.