A conductometric enzymatic methanol sensor based on polystyrene - PAMAM dendritic polymer electrospun nanofibers

Methanol (MeOH) is a solvent and cleaning agent used in industry, but it is poisonous when ingested. The recommended release threshold for MeOH vapor is 200 ppm. We present a novel sensitive micro-conductometric MeOH biosensor created by grafting alcohol oxidase (AOX) onto electrospun polystyrene-poly(amidoamine) dendritic polymer blend nanofibers (PS-PAMAM-ESNFs) on interdigitated electrodes (IDEs). The analytical performance of the MeOH microsensor was evaluated using gaseous MeOH, ethanol, and acetone samples collected from the headspace above aqueous solution with known concentration. The sensor's response time (t_Res) fluctuates from 13 s to 35 s from lower to higher concentrations. The conductometric sensor has a sensitivity of 150.53 μS.cm-1 (v/v) for MeOH and a detection limit of 100 ppm in the gas phase. The MeOH sensor is 7.3 times less sensitive to ethanol and 136.8 times less sensitive to acetone. The sensor was verified for detecting MeOH in commercial rubbing alcohol samples.

Tuning the sensing responses towards room-temperature hypersensitive methanol gas sensor using exfoliated graphene-enhanced ZnO quantum dot nanostructures

A suitable and non-invasive methanol sensor workable in ambient temperature conditions with a high response has gained wide interest to prevent detrimental consequences for industrial workers from its low-level intoxication. In this work, we present a tunable and highly responsive ppb-level methanol gas sensor device working at room temperature via a bottom-up synthetic approach using exfoliated graphene sheet (EGs) and ZnO quantum dots (QDs) on an aluminum anodic oxide (AAO) template. It is verified that EGs-supported AAO with a vertical electrode configuration enabled high and fast-responsive methanol sensing. Moreover, the hydroxyl and carboxyl groups of the high surface area EGs and ZnO QDs with a 3.37 eV bandgap efficiently absorbing UV light led to 56 times high response due to the enhanced polarization on the sensor surface compared to non-UV-radiated EGs/AAO at 800 ppb of methanol. The optimal resonance frequency of methanol is determined to be 100 kHz, which could detect methanol with high response of 2.65% at 100 ppm. The limit of detection (LOD) concentration is obtained at 2 ppb level. This study demonstrates the potential of UV-assisted ZnO, EGs, and AAO-based capacitance sensor material for rapidly detecting hazardous gaseous light organic molecules at ambient conditions, and the overall approach can be easily expanded to a novel non-invasive monitoring strategy for light and hazardous volatile organic exposures.

A sensor of liquid methanol for direct methanol fuel cells

The methanol sensors are of significance to maintain the efficient and stable operation of direct methanol fuel cells (DMFCs). The issues, including stability, the relationship between temperature, current density and concentration need, however, urgent attention. A novel electrochemical methanol sensor which is based on current output limited by methanol diffusion is developed. The stability of sensors was lifted steeply through introducing a reference electrode, narrowing the methanol flow channel, and adding a water container. The relationship between the temperature, response current and methanol concentration was determined with the help of theoretical derivation and the validity was verified by the fitting result. Other sensors can avail of this relationship to correct the temperature effect. Application test indicated that the sensor may be of great potential for the accurate monitoring of methanol concentration at the levels of DMFCs application.