Selective Gas Sensor Using Porous Silicon

High sensitive NH3 sensor based on electrochemically etched porous silicon

“…A common mechanism for determining the toxic gases of many gas sensors is a change in electrical conductivity or resistance as a result of the adsorption of gas particles (Ibraimov et al, 2016). When the gas sensor is in the air, oxygen molecules are adsorbed onto the surface of por-Si.…”

Ultrasensitive bio-detection using single-electron effect

“…Since its discovery porous Si (PS) has been the subject of much research because of its large surface area as well as its unprecedented electrical [ [1] , [2] ], optical [ [3] , [4] ], and mechanical [ [5] , [6] ] properties and its compatibility with silicon-based microelectronics [ 7 ]. Some of its current applications include areas such as optoelectronics [ 8 ], the sacrificial layer in micromachines [ 9 ], and sensors such as sensing of gas [ [10] , [11] ], proteins [ 12 ], DNA [ 13 ], organic solvents [ [14] , [15] ], bacteria [ [16] , [17] ] and viruses [ 18 ]. The needle-like structure and sharp edges that PS provides can be exploited to create very large electric fields if a metal is deposited uniformly over its surface.…”

How to Improve the Performance of Porous Silicon‐Based Gas and Vapor Sensors? Approaches and Achievements

“…proposed to using impedance spectroscopy in the frequency range of 10 3 –10 5 Hz to improve the selectivity of PSi‐based sensors. Ibraimov et al showed that the capacitance of the structure and its frequency dispersion are different under the influence of various vapors, and this difference can be used to distinguish various organic vapors such as acetonitrile, ethanol, methanol, toluene, and chloroform. The specific effect of vapors may be due to the difference in dipole moments, molar masses, and viscous lag of solvent molecules .…”

“…The use of conductivity measurement for distinguishing vapors of solvents was not so effective, because the conductance was less sensitive to vapors, especially at low frequencies. Ibraimov et al found that the characteristic response time to different vapors, and especially the recovery time after interacting with vapors, are also parameters that are sensitive to the nature of the vapor, and, therefore, the measurement of this parameter adds possibilities for selectively determining gases. It was also found that the most pronounced effect of vapors on characteristic times was observed on the frequency 1 kHz.…”