Projects / Programmes
Selective and hipersensitive microcapacitive sensor system for targetted molecular detection in the atmosphere
| Code |
Science |
Field |
Subfield |
| 2.09.03 |
Engineering sciences and technologies |
Electronic components and technologies |
Microelectronics |
| Code |
Science |
Field |
| T171 |
Technological sciences |
Microelectronics |
| Code |
Science |
Field |
| 2.10 |
Engineering and Technology |
Nano-technology |
vapour trace detection, capacitive micro-sensor, MEMS, COMB sensor, TNT
Researchers (16)
Organisations (3)
Abstract
There has been a tremendous development of new methods and principles of detection of vapour traces of targeted molecules in the atmosphere in the last decade. The goals of scientific research were directed towards the detection of low atmospheric levels of hazardous molecules, such as TNT, PETN and RDX, with the aim of securing urban environment against terrorists' threats. In the past ten years, several very different sensorial systems and methods have been developed; unfortunately, most of them suffer from poor chemical selectivity, low sensitivity and unreliability. The instrumentation is usually very big and expensive, and the time needed for accurate detection of targeted molecules is quite often very long. This is because the number of targeted molecules in the atmosphere is very low, typically in the range of 1 molecule in 10+12 to 10+14 carrier molecules. In most cases, molecular detection is based on the adsorption of targeted molecules on specially prepared surfaces of the sensors with receptor molecules. The surface coverage depends on the vapour pressure of matter, temperature, surface interactions and might be hidden by the presence of other substances, like water vapour. Targeted molecules are usually very small, their surface-coverage is incomplete and the electric signals from sensors are usually very small. We have recently demonstrated that concentrations as low as 1 molecule of TNT in 10+12 molecules of N2 can be measured (Strle et al. IEEE Sens. J. 2012) using a differential pair of chemically functionalized COMB micro-capacitors and a low noise detection electronics. To our knowledge, this is at a cutting-edge of sensitivity of any COMB sensor ever realized. The method uses low-noise CMOS technology with the sensitivity in the range of 1 attofarad. It is very robust, inherently insensitive to temperature and acoustic noise and has a great potential because of its CMOS compatibility. The goal of this project is to increase the sensitivity of this system by a factor of 100, therefore aiming at detecting 1 molecule of TNT in 10+14 molecules of a carrier gas. This means that we should be able to discern capacitance changes in the range of 10 zeptofarad (10*10-21 F). In addition, we shall seek for the solution of the inherent problem of poor chemical selectivity of the system by introducing an integrated array of up to 16 chemically differently functionalized capacitive sensors, thus mimicking the architecture of dog's nose, which is of course much more complex and by far the best molecular detection system in nature. Chemically different molecules will adsorb differently on differently functionalized surfaces and this will imprint a unique signal fingerprint to the array of micro-sensors. We aim at measuring, testing and recognizing chemically-induced electric patterns using pattern recognition algorithms. Finally, if the budget permits, we shall explore the dynamical nature of surface adsorption and desorption of target molecules by analysing the electric noise spectra from the sensors array using statistical pattern recognition algorithms. The project will be realized by a multidisciplinary team of physicists, chemists and microelectronic engineers, following a well-defined research plan and organization. This team has been successfully collaborating in similar projects for already more than seven years and has recently demonstrated one of the world's most sensitive electronic nose. In our opinion, it is possible and realistic to significantly increase the reliability, sensitivity and chemical selectivity of vapour trace recognition technology by successfully realizing this project.
Significance for science
The fundamental ARRS research project “Selective and hypersensitive microcapacity sensor systems for detection of target molecules in the atmosphere” brought together the efforts of three expert groups in the fields of physics, chemistry and micro-electronics from the University of Ljubljana and the J. Stefan Institute. The aim of the project was to solve the problem of chemical selectivity of functionalised CMOS capacitive microsensors and to increase the sensitivity for detection of explosive vapours. The project was very successfully implemented, as we built a 16 channel artificial nose demonstrator at a TRL 6 level and performed a number of measurements of the system’s response to various vapours in the atmosphere. The three above mentioned research groups previously successfully collaborated on the confidential UNos programme financed by the Slovenian Ministry of Defence and the results of the successfully finalised ARRS project are of world-class level. In the almost seven years of joint research, the main research institutions – J. Stefan Institute, Faculty of Electrical Engineering and the Faculty for Chemistry and Chemical Technology – formed close ties, which helped raise the quality of the other joint research to the very top. The results of the research were published in international peer-reviewed journal and presented at international scientific conferences. We managed to attract the attention of international public, since our demonstrator is one of the few operative multichannel artificial nose demonstrators on such a high technological level. In the scope of the research programme, we resolved all the fundamental and technological problems in the fields of physics, surface chemistry and detection of very small changes of micro-sensor capacities. The sensitivity and chemical selectivity we achieved in our demonstrator are among the best in the world. The large-scale measurements of response of the systems with 16 sensors to the controlled composition of the synthetic atmosphere with explosive molecules led to a very important conclusion. We realised that such a large volume of data could only be analysed with artificial intelligence and machine learning. The final conclusion of the project research will be published in a comprehensive review paper.
Significance for the country
The successful completion of the fundamental ARRS project “Selective and hypersensitive microcapacity sensor systems for detection of target molecules in the atmosphere” is important for Slovenia from three points of view. First, the project combined interdisciplinary research groups in the field of natural sciences and technology, which resulted in important synergies in the Slovene research space and in an increased research quality. Second, the project greatly influenced the education of young researchers, as several doctoral thesis were completed on this topic and several younger researchers participated in the project. Third, the implemented project has important role in the field of technological innovations and commercialisation. The project was brought to TRL6, which will attract potential investors. Some Slovenian companies already expressed their interest for collaboration on further commercialisation of the research results in the field of explosives detector and sensor systems to detect methane in mines. The direct long-term effects of the realised project on Slovene economy will show when we apply the results in practice. This can lead to creation of new job positions with high added value, where highly educated personnel in the field of natural science and technology could be employed, which will surely benefit the economic development of the Republic of Slovenia. The research results of the realised project will have a notable influence on the sustainably development in Slovenia. The past achievements of all three research groups in some segments are categorised as outstanding world-class achievements, which strengthens the national identity of the Republic of Slovenia. The three research groups also form an important core group that transfers international scientific achievements to Slovenian science and technology and invests into popularisation of science among the general public. Our successful studies are the key to successful organisation and implementation of graduate and post-graduate study programmes/courses. Within the group, several doctoral candidates successfully finished their doctorates and later on gained employment as highly qualified workers in Slovenian high-tech companies. Participation in international (EU) projects in specialised fields leads to active participation in international studies and development in the field of sensors and scientific cooperation with the best scientists and research institutions in the world. This support of excellent scientific and technological research will allow the new high-tech industry in Slovenia to enter the international market as an equal.
Most important scientific results
Annual report
2013,
2014,
2015,
final report
Most important socioeconomically and culturally relevant results
Annual report
2013,
2014,
2015,
final report
