Recent Advances in Nanomechanical Membrane-Type Surface Stress Sensors towards Artificial Olfaction

Abstract

Nanomechanical sensors have gained significant attention as powerful tools for detecting, distinguishing, and identifying target analytes, especially odors that are composed of a complex mixture of gaseous molecules. Nanomechanical sensors and their arrays are a promising platform for artificial olfaction in combination with data processing technologies, including machine learning techniques. This paper reviews the background of nanomechanical sensors, especially conventional cantilever-type sensors. Then, we focus on one of the optimized structures for static mode operation, a nanomechanical Membrane-type Surface stress Sensor (MSS), and discuss recent advances in MSS and their applications towards artificial olfaction.

Detection of Trace Amounts of Water in Organic Solvents by DNA-Based Nanomechanical Sensors

“…Since nanomechanical sensors including the MSS can obtain efficient signal responses to sorption-induced mechanical deformation of a bulk receptor material [ 26 , 39 ], we coated DNA on the membrane of an MSS by an inkjet spotter. The coating thickness was varied by changing the number of droplets of inkjet spotting ( N ) in the range from 100 to 1000.…”

“…The membrane is coated with a receptor material (in the present study, DNA). When the receptor layer deforms upon the sorption of the target analytes, the receptor layer generates surface stress on the membrane [ 26 ]. The surface stress is transduced to the four sensing beams as amplified uniaxial stress, resulting in changes in the electrical resistance of the piezoresistors embedded in the beams.…”

“…Focusing on the changes in mechanical properties associated with DNA hydration, nanomechanical sensors have attracted attention as potential sensing platforms to detect the mechanical deformation of receptor layers caused by the sorption of target molecules and hence have been applied to measuring DNA hydration [ 17 , 18 , 20 ], mechanical properties [ 18 , 19 ] and hybridization [ 18 , 21 ]. The hybridization behavior of DNA has led to the development of DNA-based nanomechanical sensors for various applications [ 22 , 23 , 24 , 25 , 26 ]. Although there is a limited number of papers using DNA as a receptor material for nanomechanical sensors to detect water vapor, albeit for different purposes (i.e., the detection of hydration) [ 17 , 20 ], DNA-based nanomechanical sensors have mostly been applied in aqueous environment because of their potential applications [ 24 , 25 ].…”

“…In this work, we found that a DNA-based nanomechanical sensor exhibited high selectivity to water vapor. We used one of the nanomechanical sensors operating in the so-called static mode, a Membrane-type Surface stress Sensor (MSS) [ 26 , 34 ], and deposited natural DNA obtained from salmon testes onto the MSS. Compared to nanomechanical sensors in dynamic mode operation [ 25 ] as well as to other types of gas and chemical sensors [ 35 ], nanomechanical sensors in static mode operation detect mechanical stress/strain [ 26 ] and hence transduce the mechanical deformation induced by the swelling of a DNA layer associated with DNA hydration, resulting in high sensitivity to water.…”

“…We used one of the nanomechanical sensors operating in the so-called static mode, a Membrane-type Surface stress Sensor (MSS) [ 26 , 34 ], and deposited natural DNA obtained from salmon testes onto the MSS. Compared to nanomechanical sensors in dynamic mode operation [ 25 ] as well as to other types of gas and chemical sensors [ 35 ], nanomechanical sensors in static mode operation detect mechanical stress/strain [ 26 ] and hence transduce the mechanical deformation induced by the swelling of a DNA layer associated with DNA hydration, resulting in high sensitivity to water. Owing to the high sensitivity and selectivity of the examined sensor to water vapor, we also demonstrate in this work that trace amounts of water in organic solvents can be detected.…”