دكتوراه
العلوم والتقنية
The University of Sheffield
مجال التميز | تميز دراسي و بحثي |
البحوث المنشورة |
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البحث (1): | |
عنوان البحث: | Sub-nanomolar detection of cesium with water-gated transistor |
رابط إلى البحث: | https://aip.scitation.org/doi/10.1063/1.5108730 |
تاريخ النشر: | 09/08/2019 |
موجز عن البحث: | Cesium (Cs+) cations are rare in nature, but the β− active radioisotope 137Cs can be released from nuclear accidents and find its way into the water supply, where it is harmful to humans and animals who drink it. We here report a water-gated thin film transistor (WGTFT) that allows the detection of Cs+ in drinking water at very low concentrations. The transistor channel is formed from spray-pyrolyzed tin dioxide, SnO2, which gives WGTFTs with near-zero initial threshold. When the WGTFT is sensitized with a plasticized PVC membrane containing the Cs+-selective zeolite “mordenite,” it displays a threshold shift when exposed to drinking water samples carrying traces of Cs+. The response characteristic is given by the Langmuir adsorption isotherm instead of the Nikolsky-Eisenman law commonly found for ion-sensitive WGTFTs sensitized with organic ionophores. We find a complex stability constant K = (3.9 ± 0.4) × 109 l/mol and a limit of detection (LoD) of 33 pM. Our LoD is far lower than the Cs+ potability limit of 7.5 nM, which cannot be met by organic-sensitized membranes where the LoD is typically in the order of 100 nM or more. |
البحث (2): | |
عنوان البحث: | Monitoring the lead-and-copper rule with a water-gated field effect transistor |
رابط إلى البحث: | https://iwaponline.com/jwh/article/18/2/159/72371/Monitoring-the-lead-and-copper-rule-with-a-water |
تاريخ النشر: | 20/02/2020 |
موجز عن البحث: | We use the natural zeolite clinoptilolite as the sensitive element in a plasticised PVC membrane. Separating a sample pool and a reference pool with such a membrane in water-gated SnO2 thin-film transistor (SnO2 WGTFT) leads to membrane potential, and thus transistor threshold shift in response to the common drinking water pollutants Pb2+ or Cu2+ in the sample pool. Threshold shift with ion concentration, c, follows a Langmuir-Freundlich (LF) characteristic. As the LF characteristic shows the steepest slope in the limit c → 0, this opens a window to limits-of-detection (LoDs) far below the ‘action levels’ of the ‘lead-and-copper rule’ for drinking water: Pb2+: LoD 0.9 nM vs 72 nM action level, Cu2+: LoD 14 nM vs 20.5 μM action level. LoDs are far lower than for membranes using organic macrocycles as their sensitive elements. Threshold shifts at the lead and copper action levels are more significant than shifts in response to variations in the concentration of non-toxic co-cations, and we discuss in detail how to moderate interference. The selective response to lead and copper qualifies clinoptilolite-sensitised WGTFTs as a low footprint sensor technology for monitoring the lead-and-copper rule, and to confirm the effectiveness of attempts to extract lead and copper from water. |
البحث (3): | |
عنوان البحث: | Sensing aromatic pollutants in water with catalyst-sensitized water-gated transistor |
رابط إلى البحث: | https://link.springer.com/article/10.1007/s11696-020-01212-3 |
تاريخ النشر: | 05/06/2020 |
موجز عن البحث: | Some materials that are active heterogeneous catalysts for the breakdown of non-ionic aromatic solutes in water are found to act as potentiometric sensitizers for same solutes. As an example, here the aromatic water pollutant, benzyl alcohol, was sensed with a limit of detection below its potability limit of 19 μM. Our findings are rationalized on the grounds that both catalysis and sensing rely on adhesion of analyte/substrate on the sensitizer/catalyst. Specifically, a set of powdered transition metal-doped zeolites and related frameworks that catalyze the oxidation of waterborne aromatic pollutants were dispersed in phase transfer matrices. Matrices were introduced into water-gated thin film transistors that act as potentiometric transducers. Potentiometric sensing of non-ionic waterborne pollutants is limited to molecules with a ‘free’ molecular dipole, i.e., a dipole that is not locked in the molecular plane. The present work establishes an application for catalysts beyond catalysis itself. The use of catalysts as sensitizers is recommended for wider uptake and in reverse, to screen candidate catalysts. |
المؤتمرات العلمية |
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المؤتمر (1): | |
عنوان المؤتمر: | UK Semiconductors 2019 conference |
تاريخ الإنعقاد: | 01/07/2019 |
مكان الإنعقاد: | Sheffield, UK |
طبيعة المشاركة: | Oral presentation |
عنوان المشاركة: | Sub-nanomolar detection of Caesium with water-gated transistor |
ملخص المشاركة: | Cesium (Cs+) cations are rare in nature, but the β− active radioisotope 137Cs can be released from nuclear accidents and find its way into the water supply, where it is harmful to humans and animals who drink it. We here report a water-gated thin film transistor (WGTFT) that allows the detection of Cs+ in drinking water at very low concentrations. The transistor channel is formed from spray-pyrolyzed tin dioxide, SnO2, which gives WGTFTs with near-zero initial threshold. When the WGTFT is sensitized with a plasticized PVC membrane containing the Cs+-selective zeolite “mordenite,” it displays a threshold shift when exposed to drinking water samples carrying traces of Cs+. The response characteristic is given by the Langmuir adsorption isotherm instead of the Nikolsky-Eisenman law commonly found for ion-sensitive WGTFTs sensitized with organic ionophores. We find a complex stability constant K = (3.9 ± 0.4) × 109 l/mol and a limit of detection (LoD) of 33 pM. Our LoD is far lower than the Cs+ potability limit of 7.5 nM, which cannot be met by organic-sensitized membranes where the LoD is typically in the order of 100 nM or more. |
الرابط: | https://uksemiconductors.com/wp-content/uploads/2019/06/UKS2019_TechnicalProgramme2.pdf |