Selective detection of complex gas mixtures using point contacts: concept, method and tools

Abstract

Of all modern nanosensors using the principle of measuring variations in electric conductance, point-contact sensors stand out in having a number of original sensor properties not manifested by their analogues. The nontrivial nature of point-contact sensors is based on the unique properties of Yanson point contacts used as the sensing elements. The quantum properties of Yanson point contacts enable the solution of some of the problems that could not be solved using conventional sensors measuring conductance. In the present paper, we demonstrate this by showing the potential of quantum point-contact sensors to selectively detect components of a gas mixture in real time. To demonstrate the high efficiency of the proposed approach, we analyze the human breath, which is the most complex of the currently known natural gas mixtures with extremely low concentrations of its components. Point-contact sensors allow us to obtain a spectroscopic profile of the mixture. This profile contains information about the complete set of energy interactions occurring in the point contact/breath system when the breath constituents adsorb to and desorb from the surface of the point-contact conduction channel. With this information we can unambiguously characterize the analyzed system, since knowing the energy parameters is key to successfully identifying and modeling the physicochemical properties of various quantum objects. Using the point-contact spectroscopic profile of a complex gas mixture it is possible to get a functional dependence of the concentration of particular breath components on the amplitude of the sensor output signal. To demonstrate the feasibility of the proposed approach, we analyze the point-contact profiles from the breath of several patients and compare them with the concentrations of serotonin and cortisol in the body of each patient. The obtained results demonstrate that the proposed methodology allows one to get an effective calibration function for a non-invasive analysis of the level of serotonin and cortisol in the human body using the point-contact breath test. The present study indicates some necessary prerequisites for the design of fast detection methods using differential sensor analysis in real time, which can be implemented in various areas of science and technology, among which medicine is one of the most important.

Quantum mechanisms for selective detection in complex gas mixtures with conductive sensors: analysis of the problem and new results

“…Quantum systems of electrons and phonons in a metal can serve as a tool to selectively detect various external agents [20,25,35]. The interaction of electrons and phonons with each other or with the atoms and molecules adsorbed on the surface of the sensor's sensing element makes it possible to obtain all necessary energy information about the sensor material, as well as the data needed to identify the analyzed agent [25]. The energy approach is a universal principle that ensures the absolute selectivity of quantum sensors [32].…”

“…This allows separation of the nonlinear current phenomena and the thermal effects in the contact, transferring the manifestation of the latter to a space far beyond the contact. As a result, the Yanson point contact can be used as a sensing element of a quantum sensor that operates effectively at room temperature [25,26,32]. At the same time, it should be noted that the use of the repeatedly proven technology of the Yanson point contact spectroscopy ensures the creation of point contacts with well-reproducible properties.…”

“…The technology for creating point-contact sensors for studying human breath is described in detail in Refs. [24,25,44,45]. The main elements of the process of creating dendritic Yanson point contacts are presented in Refs.…”

“…To decipher the spectral pro le of breath obtained using point-contact sensors, both the various spectral analysis techniques already tested in the Yanson point-contact spectroscopy can be used [34,36] and new approaches to extraction of the necessary information can be developed [25,51]. The idea implemented in Ref.…”

Portable Device for Multipurpose Research on Dendritic Yanson Point Contacts and Quantum Sensing

“…Quantum structures are ideal objects by which to discover and study new sensor mechanisms and implement advanced approaches in sensor analysis to develop innovative sensor devices [ 1 , 2 , 3 ]. They are able to provide the necessary conditions for the development of sensor technologies based on new principles that are fundamentally different from the methodology currently used to create traditional sensor devices.…”