Bartosz Wyszynski

Molecularly Imprinted Sol-Gel-Based QCM Sensor Arrays for the Detection and Recognition of Volatile Aldehydes

The detection and recognition of metabolically derived aldehydes, which have been identified as important products of oxidative stress and biomarkers of cancers; are considered as an effective approach for early cancer detection as well as health status monitoring. Quartz crystal microbalance (QCM) sensor arrays based on molecularly imprinted sol-gel (MISG) materials were developed in this work for highly sensitive detection and highly selective recognition of typical aldehyde vapors including hexanal (HAL); nonanal (NAL) and bezaldehyde (BAL). The MISGs were prepared by a sol-gel procedure using two matrix precursors: tetraethyl orthosilicate (TEOS) and tetrabutoxytitanium (TBOT). Aminopropyltriethoxysilane (APT); diethylaminopropyltrimethoxysilane (EAP) and trimethoxy-phenylsilane (TMP) were added as functional monomers to adjust the imprinting effect of the matrix. Hexanoic acid (HA); nonanoic acid (NA) and benzoic acid (BA) were used as psuedotemplates in view of their analogous structure to the target molecules as well as the strong hydrogen-bonding interaction with the matrix. Totally 13 types of MISGs with different components were prepared and coated on QCM electrodes by spin coating. Their sensing characters towards the three aldehyde vapors with different concentrations were investigated qualitatively. The results demonstrated that the response of individual sensors to each target strongly depended on the matrix precursors; functional monomers and template molecules. An optimization of the 13 MISG materials was carried out based on statistical analysis such as principle component analysis (PCA); multivariate analysis of covariance (MANCOVA) and hierarchical cluster analysis (HCA). The optimized sensor array consisting of five channels showed a high discrimination ability on the aldehyde vapors; which was confirmed by quantitative comparison with a randomly selected array. It was suggested that both the molecularly imprinting (MIP) effect and the matrix effect contributed to the sensitivity and selectivity of the optimized sensor array. The developed MISGs were expected to be promising materials for the detection and recognition of volatile aldehydes contained in exhaled breath or human body odor.

Odor sensing system using ball SAW devices functionalized with self-assembled lipid-derivatives and GC materials

We present application of a novel method for fabrication of highly sensitive spherical surface acoustic wave (ball-SAW) odor sensors, using self-assembling of lipopolymers, lipids and GC (gas chromatography) materials. The method allows good control over the thickness of the odor-sensitive layer - an important feature for sensitivity enhancement of the ball-SAW sensors. The fabrication method consists of (i) chemisorption of a lipid-derivative(s), and (ii) physical sorption of GC stationary-phase materials inside the lipid-derivatives matrix. Ball-SAW sensors fabricated using this method have very high sensitivity to n-butanol in both dry- and humidified-air with detection limits well below human threshold.

Odor Recorder Capable of Wide Dynamic Recordable Range Based on Higher Order Sensing and Signal Extraction Technique for Small Signal

The odor recording method for extending dynamic recordable range was proposed. In this method, the enriched information obtained from higher order sensing based on preconcentrator with variable temperature was utilized so that the contribution of component with small ratio to sensor response could be separately extracted from that of the main component. Then, the signal extraction technique for small signal was developed using Savitzky-Golay filter for qualitative and quantitative detection of component with small ratio, and then this extracted information was used in recording process. It was found that the target odors including component with small ratio down to 1% were successfully recorded using this proposed method. This method is useful to extend the dynamic recordable range especially in the case that the component with high contribution in impression has low contribution to sensor responses.

Highly sensitive QCM odor-sensors functionalized with self-assembled lipid-derivatives and GC materials

We present a novel method for fabrication of highly sensitive quartz crystal microbalance (QCM) odor sensors using combined chemical- and physical sorption processes. In conventional techniques used for fabrication of the QCM sensors (e.g. spray-coating, atomizer) a bulky and costly setup is usually required. Here, we propose a simple method for functionalization of QCMs consisting in (i) chemisorption of a lipid-derivative(s) and then (ii) physical sorption of gas-chromatography (GC) stationary-phase materials from their ethanolic solutions. The materials self-organize on the sensor surface and the QCMs fabricated this way have sensitivity toward airborne odorants much higher than the sensors fabricated using conventional atomizer technique.

Array of Chemosensitive Resistors with Composites of Gas Chromatography (GC) Materials and Carbon Black for Detection and Recognition of VOCs: A Basic Study

Mimicking the biological olfaction, large odor-sensor arrays can be used to acquire a broad range of chemical information, with a potentially high degree of redundancy, to allow for enhanced control over the sensitivity and selectivity of artificial olfaction systems. The arrays should consist of the largest possible number of individual sensing elements while being miniaturized. Chemosensitive resistors are one of the sensing platforms that have a potential to satisfy these two conditions. In this work we test viability of fabricating a 16-element chemosensitive resistor array for detection and recognition of volatile organic compounds (VOCs). The sensors were fabricated using blends of carbon black and gas chromatography (GC) stationary-phase materials preselected based on their sorption properties. Blends of the selected GC materials with carbon black particles were subsequently coated over chemosensitive resistor devices and the resulting sensors/arrays evaluated in exposure experiments against vapors of pyrrole, benzenal, nonanal, and 2-phenethylamine at 150, 300, 450, and 900 ppb. Responses of the fabricated 16-element array were stable and differed for each individual odorant sample, proving the blends of GC materials with carbon black particles can be effectively used for fabrication of large odor-sensing arrays based on chemosensitive resistors. The obtained results suggest that the proposed sensing devices could be effective in discriminating odor/vapor samples at the sub-ppm level.

PEG Lipopolymers as Coatings for QCM Odor Sensors. Effect of Tether's Chain-length

Application of quartz crystal microbalance (QCM) sensors for odor sensing has been an important research topic. Proper performance of odor sensing systems with QCM sensors requires good discrimination among odor samples. Recently we have been studying pegylated lipopolymers -composed of lipid and poly(ethylene glycol). (PEG) The materials allowed for very good discrimination among odorants of different functional groups. Here we study lipopolymers with various molecular weight of PEG moiety. Our results indicate that the PEG chain length is an important factor influencing lipopolymers sensing properties.