Sensitivity of EGFET pH Sensors with TiO2 Nanowires

Li, J.-Y.; Chang, Shih-sen; Chang, Sheng-Po; Tsai, Tsung-Ying

doi:10.1149/2.0091410ssl

Cited by 35 publications

(10 citation statements)

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“…Figure a shows a consistent drift of the saturation current with a time of ≈18.6 µA h −1 . Reported sensitivities ( S ) for EGFET pH systems, extracted under similar saturation conditions, range between 15.8 and 79.9 µA pH −1 . Noteworthy, the extraction of S values in A pH −1 from the output plot ( I ds vs V ds ) of the transistor in saturation mode ( V ds ≥ V eff ) is not recommended because pH variation results in a shift in V gs (i.e., pH ∝ V gs ) which modulates the drain‐to‐source current ( I ds ).…”

Section: Resultsmentioning

confidence: 99%

“…Figure e,f provides similar plots for the ZnO EGFET in linear mode ( V ref = 3 V, V ds = 0.3 V) and all instances are given in Figure S4e–h (Supporting Information). S extraction in linear mode is typically reported by choosing a fixed drain current value and identifying the intersection points with V ref for different pH values . Nonetheless, this method is not recommended for two reasons.…”

Section: Resultsmentioning

confidence: 99%

“…For instance, the response time is defined by Wei et al as the time needed for a sensor to reach 90% of its final value, but, since all pH sensors experience a constant drift with time, the final value is unclear . Commonly investigated ISFET and EGFET pH sensing systems use a commercial reference electrode, but the reference electrodes' properties and behavior are rarely reported, which leads to erroneously attributing their effect to the investigated sensing material. To give an example, solution‐filled reference electrodes can have response times in the range of tens of seconds while gel‐filled reference electrodes can have tens of minutes of stabilization time .…”

Section: Introductionmentioning

confidence: 99%

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A Protocol to Characterize pH Sensing Materials and Systems

et al. 2018

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Although significant progress is made in identifying pH sensing materials and device configurations, a standard protocol for benchmarking performance of next-generation pH devices is still lacking. In particular, key properties of characterization systems, such as inherent component contributions, time plots for extended-gate field-effect transistor (EGFET) measurements, and the input resistance (R in ), often go unreported in studies of pH sensing systems. These properties strongly influence the characterization system and can lead to mistaken attribution of properties to the device. In this paper, a series of essential characterization tests and parameters are reported to evaluate pH systems, such as the zinc oxide EGFET, in a standardized protocol. This EGFET ZnO sensor has a sensitivity of −58.1 mV pH −1 , drift range from 2.5 to 14.2 µA h −1 , and response time of 136 s. By using a ZnO sensing electrode, it is demonstrated that i) intrinsic contributions of reference electrode and commercial transistor (for EGFET) are not negligible; ii) time plots for EGFET configuration and defining a critical point at the onset of drift are essential for accurate sensitivity, response time, and drift reporting; and iii) the results of the pH sensing system are strongly dependent on the input resistance of the used characterization instruments. pH Sensor Benchmarking

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Protocol to Characterize pH Sensing Materials and Systems

et al. 2018

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“…Thus, a large C OX and high µ can improve the sensing current of ISFET sensors and so as to boost the signal-to-noise margin. Several high-κ dielectric membranes like Al 2 O 3 [9], ZnO [10], TiO 2 [11], ZrO 2 [12], SnO 2 [13], Ta 2 O 5 and WO 3 [14] were applied for pH-ISFET. Moreover, nanostructures have been used to increase the contact area of the active sensor area.…”

Section: Introductionmentioning

confidence: 99%

Ion-sensitive field-effect transistor with sSi/Si0.5Ge0.5/sSOI quantum-well for high voltage sensitivity

Wen

Liu

et al. 2016

Microelectronic Engineering

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“…EGFET enables the isolation of the sensing membrane apart from the MOS-FET part and offers numbers of advantages including cost-effective fabrication, simple structure, packaging simplicity, long term stability, resistance to light and temperature and also disposable gate. 1,2 In constructing an extending gate, beside a variety of metallic thin films, nanoporous materials act as a potential candidate for sensing membrane materials owing to its higher surface area to volume ratio than the planar surface due to its three-dimensional topography which inherently results in signal amplification. 3,4 Small pore diameter establishment has greatly targeted and aroused attention in sensor fabrication due to its excellent capabilities in providing greater sensitivity and performance related to the reinforcement of ion transport and molecules translocation.…”

mentioning

confidence: 99%

A Colloidal Nanopatterning and Downscaling of a Highly Periodic Au Nanoporous EGFET Biosensor

Purwidyantri

Kamajaya

Chen

et al. 2018

J. Electrochem. Soc.

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The nanopattern of highly ordered and uniform Au nanoporous membranes with different sizes and thicknesses and the downscaling approach through the combination of colloidal based nanosphere lithography (NSL) and thermal evaporation was proposed to fabricate an extending-gate field effect transistor (EGFET) membrane. The fabrication involved the use of PS nanospheres templates of 500 nm and 100 nm in diameters and various Au thickness of 10, 25 and 40 nm. Carried out in the detection of Staphylococcus aureus 16S rRNA hybridization test with analytical range of 10 1 -10 6 pM DNA targets, the smaller the Au nanoporous diameter made up by the thicker Au layer produced a gradual improvement in potentiometric study. The Au-nanoporous produced by the thickest Au film at 40 nm and smaller diameter of PS nanospheres (100 nm) demonstrated the most optimum threshold voltage shift and limit of detection (LOD) of ∼1 pM altogether with remarkable specificity in the presence of highly concentrated non-specific DNA of other pathogens. Analytical outcomes point out that smaller, periodic and uniform nanoporous EGFET membrane facilitated the larger hybridization signal due to the higher active surface area enabling the more optimum control of DNA orientation and immobilization. The replacement of Ion Selective Field Effect Transistor (ISFET) with extending gate FET (EGFET) structure has brought electrochemical DNA sensor to a new era of semiconductor genetics. EGFET enables the isolation of the sensing membrane apart from the MOS-FET part and offers numbers of advantages including cost-effective fabrication, simple structure, packaging simplicity, long term stability, resistance to light and temperature and also disposable gate. 1,2In constructing an extending gate, beside a variety of metallic thin films, nanoporous materials act as a potential candidate for sensing membrane materials owing to its higher surface area to volume ratio than the planar surface due to its three-dimensional topography which inherently results in signal amplification.3,4 Small pore diameter establishment has greatly targeted and aroused attention in sensor fabrication due to its excellent capabilities in providing greater sensitivity and performance related to the reinforcement of ion transport and molecules translocation. 5,6 Numbers of studies focused on porous FET with a range of size from meso to macropores (nm scales) and with different materials. Semiconductive organic network, e.g Ni 3 (HITP) 2 , 7 nanoporous silicon 8-10 and porous platinum 11 have also been proven effective in numbers of chemical sensors since they provide a wide range of application on voltage-gated ion channels or microfluidic chips beneficial for sensitivity improvement in ion or gas sensor. Nevertheless, these nanoporous structures are somehow generated in a z E-mail: cslai@mail.cgu.edu.tw randomly disoriented structure while the downscaling of the pore size with simple and cost-effective techniques and instrumentation remains challenging. The emergence of a highly oriente...

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Sensitivity of EGFET pH Sensors with TiO2 Nanowires

Cited by 35 publications

References 0 publications

A Protocol to Characterize pH Sensing Materials and Systems

A Protocol to Characterize pH Sensing Materials and Systems

Ion-sensitive field-effect transistor with sSi/Si0.5Ge0.5/sSOI quantum-well for high voltage sensitivity

A Colloidal Nanopatterning and Downscaling of a Highly Periodic Au Nanoporous EGFET Biosensor

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