A membrane-free cation selective water-gated transistor

Althagafi, Talal M.; Baroot, Abbad Al; Algarni, Saud A.; Grell, Martin

doi:10.1039/c6an00967k

Cited by 8 publications

(23 citation statements)

References 30 publications

(63 reference statements)

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“…As V M adds to the applied gate voltage it can be measured as a shift in the WGTFT's threshold V th . We therefore recorded linear transfer characteristics using a standard transistor characterisation setup reported earlier [6,8]. After 30 seconds of exposure each time new electrolyte was filled into the outer pool as described in 2.4, we scanned V G from -0. .…”

Section: Wgtft Characterisation and Analysismentioning

confidence: 99%

“…Same analysis has been used previously in other WGTFT sensors work, e.g. [2,6,8]. Finally, data were presented in appropriate plots (Inset Fig.…”

Section: Wgtft Characterisation and Analysismentioning

confidence: 99%

“…An important sub-genre of WGTFTs are the ion-selective WGTFTs, first introduced by List-Kratochvil [5]. So far, the sensitiser in such devices always was an organic 'ionophore', for example a crown ether [6], calixarene [7,8], or valinomycin [9]. Typical 'target' ions are K + , Na + , Li + , Ca 2+ , Mg 2+ [10].…”

Section: Introductionmentioning

confidence: 99%

“…The ionophore is often introduced into the WGTFT within a plasticised PVC membrane, for example in a 2-chamber design [5] similar as in classical electrochemical potentiometry [11,12], or by direct application of the membrane onto the gate contact [6], or the semiconducting channel [9], of the WGTFT. Also, membrane-free ion sensitive WGTFTs have been demonstrated [8] where the ionophore is incorporated into the semiconducting channel. WGTFT sensors are typically formed using solution-processed semiconductors, e.g.…”

Section: Introductionmentioning

confidence: 99%

“…WGTFT sensors are typically formed using solution-processed semiconductors, e.g. semiconducting polymers [3,6,8], precursor-route metal oxides [6], or carbon nanotubes [9]. Selective binding of waterborne ions in the gating water to the ionophore leads to a membrane potential, V M , and consequential shift in V th .…”

Section: Introductionmentioning

confidence: 99%

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Sub-nanomolar detection of cesium with water-gated transistor

Alghamdi

Alqahtani

Grell

2019

Journal of Applied Physics

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Caesium (Cs +) cations are active radioisotope 137 Cs can be released in nuclear incidents and find its way into the water supply, where it is harmful to humans and animals drinking it. We here report a water-gated thin film transistor (WGTFT) which allows the detection of Cs + in drinking water at very low concentrations. The transistor channel is formed from spray pyrolysed tin dioxide, SnO 2 which gives WGTFTs with near-zero initial threshold. When the WGTFT is sensitised with a plasticised 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 sensitised with organic ionophores. We find a complex stability constant K = (3.9 +/-0.4) x 10 9 L / mole 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 organicsensitised membranes where LoD is typically in the order of 100 nM or more.

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Section: Wgtft Characterisation and Analysismentioning

confidence: 99%

“…Same analysis has been used previously in other WGTFT sensors work, e.g. [2,6,8]. Finally, data were presented in appropriate plots (Inset Fig.…”

Section: Wgtft Characterisation and Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Sub-nanomolar detection of cesium with water-gated transistor

Alghamdi

Alqahtani

Grell

2019

Journal of Applied Physics

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Comparing electron- and hole transporting semiconductors in ion sensitive water- gated transistors

Baroot

Grell

2019

Materials Science in Semiconductor Processing

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We present a systematic study comparing different solution-processed semiconductors in cation-sensitive water-gated thin film transistors (WGTFTs): A hole transporting semiconducting polymer (rrP3HT), and an electron-transporting precursor-route metal oxide (ZnO). To allow comparison, we used the same ionophore to sensitise the gate contact for both semiconductors. We find both organic hole transporter and inorganic electron transporter have their relative merits, and drawbacks, in ion-sensitive WGTFTs. Hole transporting rrP3HT WGTFTs show low hysteresis under water-gating and give super-Nernstian sensitivity. However, rrP3HT responds to ionic strength in water even when WGTFTs are not sensitised, compromising selectivity. Electron transporting ZnO WGTFTs show higher mobility, but also stronger hysteresis, and sub-Nernstian response. However, ZnO WGTFTs show little response to ionic strength when not sensitised. We rationalise the super-versus-sub-Nernstian sensitivities via a capacitive amplification/attenuation effect. Our study suggests that the optimum semiconductor material for ion-selective WGTFTs would be a precursor-route inorganic hole transporting semiconductor.

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