Mapping the dielectric constant of a single bacterial cell at the nanoscale with scanning dielectric force volume microscopy

Checa, Martí; Millán-Solsona, Rubén; Blanco, Nuria; Torrents, Eduard; Fabregas, Rene; Gomila, Gabriel

doi:10.1039/c9nr07659j

Cited by 15 publications

(52 citation statements)

References 60 publications

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“…In‐liquid SDM measurements on the EGOFET in operando were performed by operating the technique in the so‐called force volume mode (see Section S3, Supporting Information), recently introduced in air environment. [ 34 ] We analyzed an area of the transistor which comprises of the source–channel–drain, as shown by the AFM topographic image in Figure a. The channel length is around 30 µm and presents some clearly visible nanoscale morphological heterogeneities, including some holes in the semiconductor layer (from where the thickness of the organic thin film layer was estimated to be 20–30 nm).…”

Section: Resultsmentioning

confidence: 99%

“…These images are obtained from the local electric force–voltage transfer curves by selecting the values corresponding to a given gate voltage at the selected tip–sample distance. [ 34 ] Figure a shows examples of electric images obtained for a tip–channel distance Z = 180 nm with respect to the surface of the semiconductor (electric images for different Z can be found in Section S10, Supporting Information) and for gate voltages V GS from 0 to −0.6 V. Concerning the semiconductor channel, when the gate voltage is below the threshold voltage (off‐state) it shows an almost uniform and symmetric distribution of the electric forces (except for edge effects), which is independent from the gate voltage (see black, red, and blue central average cross‐section profiles in Figure 3b). When the gate voltage passes the threshold voltage ( V GS < −0.2 V), we observe a change in the contrast of the electric images, which reflects an increase in the force acting on the tip in all parts of the device.…”

Section: Resultsmentioning

confidence: 99%

“…The so‐called force volume mode had been used to acquire the data, as described in the text and previously applied in air. [ 34 ] Normal deflection and A ωmod oscillation amplitude approach curves were acquired using the JPK Nanowizard 4 AFM system (JPK) connected to an external lock in (eLockin 204/2, Anfatec). The acquisition was performed by using the Advanced Quantitative Imaging (JPK) mode.…”

Section: Methodsmentioning

confidence: 99%

“…Concerning the spatial resolution and acquisition times, we expect that sub-100 nm and sub-30 s images could be obtained on EGOFETs with the use of high resonance frequency probes. [34,35]…”

Section: (6 Of 8)mentioning

confidence: 99%

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Nanoscale Mapping of the Conductivity and Interfacial Capacitance of an Electrolyte‐Gated Organic Field‐Effect Transistor under Operation

Kyndiah

Checa

Leonardi

et al. 2020

Adv Funct Materials

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Probing nanoscale electrical properties of organic semiconducting materials at the interface with an electrolyte solution under externally applied voltages is key in the field of organic bioelectronics. It is demonstrated that the conductivity and interfacial capacitance of the active channel of an electrolyte‐gated organic field‐effect transistor (EGOFET) under operation can be probed at the nanoscale using scanning dielectric microscopy in force detection mode in liquid environment. Local electrostatic force versus gate voltage transfer characteristics are obtained on the device and correlated with the global current–voltage transfer characteristics of the EGOFET. Nanoscale maps of the conductivity of the semiconducting channel show the dependence of the channel conductivity on the gate voltage and its variation along the channel due to the space charge limited conduction. The maps reveal very small electrical heterogeneities, which correspond to local interfacial capacitance variations due to an ultrathin non‐uniform insulating layer resulting from a phase separation in the organic semiconducting blend. Present results offer insights into the transduction mechanism at the organic semiconductor/electrolyte interfaces at scales down to ≈100 nm, which can bring substantial optimization of organic electronic devices for bioelectronic applications such as electrical recording on excitable cells or label‐free biosensing.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: (6 Of 8)mentioning

confidence: 99%

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Nanoscale Mapping of the Conductivity and Interfacial Capacitance of an Electrolyte‐Gated Organic Field‐Effect Transistor under Operation

Kyndiah

Checa

Leonardi

et al. 2020

Adv Funct Materials

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“…Therefore, the permittivity of bacterial cells on the influence of external electric fields depends on their species, type (gram-positive or gram-negative) [107,109,110], as well as on the electrical conductivity and permittivity of various intracellular components of bacteria. In addition, they may depend on the physiological state of bacteria (metabolic activity level, degree of viability), as well as on living conditions and the state of their hydration [111][112][113].…”

Section: Microwave Label-free Biosensorsmentioning

confidence: 99%

Label-Free Biosensors for Laboratory-Based Diagnostics of Infections: Current Achievements and New Trends

et al. 2020

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Infections pose a serious global public health problem and are a major cause of premature mortality worldwide. One of the most challenging objectives faced by modern medicine is timely and accurate laboratory-based diagnostics of infectious diseases. Being a key factor of timely initiation and success of treatment, it may potentially provide reduction in incidence of a disease, as well as prevent outbreak and spread of dangerous epidemics. The traditional methods of laboratory-based diagnostics of infectious diseases are quite time- and labor-consuming, require expensive equipment and qualified personnel, which restricts their use in case of limited resources. Over the past six decades, diagnostic technologies based on lateral flow immunoassay (LFIA) have been and remain true alternatives to modern laboratory analyzers and have been successfully used to quickly detect molecular ligands in biosubstrates to diagnose many infectious diseases and septic conditions. These devices are considered as simplified formats of modern biosensors. Recent advances in the development of label-free biosensor technologies have made them promising diagnostic tools that combine rapid pathogen indication, simplicity, user-friendliness, operational efficiency, accuracy, and cost effectiveness, with a trend towards creation of portable platforms. These qualities exceed the generally accepted standards of microbiological and immunological diagnostics and open up a broad range of applications of these analytical systems in clinical practice immediately at the site of medical care (point-of-care concept, POC). A great variety of modern nanoarchitectonics of biosensors are based on the use of a broad range of analytical and constructive strategies and identification of various regulatory and functional molecular markers associated with infectious bacterial pathogens. Resolution of the existing biosensing issues will provide rapid development of diagnostic biotechnologies.

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Automated Scanning Dielectric Microscopy Toolbox for Operando Nanoscale Electrical Characterization of Electrolyte‐Gated Organic Transistors

Tanwar,

Millan‐Solsona,

Ruiz‐Molina

et al. 2024

Adv Elect Materials

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Electrolyte‐gated organic transistors (EGOTs) leveraging organic semiconductors' electronic and ionic transport characteristics are the key enablers for many biosensing and bioelectronic applications that can selectively sense, record, and monitor different biological and biochemical processes at the nanoscale and translate them into macroscopic electrical signals. Understanding such transduction mechanisms requires multiscale characterization tools to comprehensively probe local electrical properties and link them with device behavior across various bias points. Here, an automated scanning dielectric microscopy toolbox is demonstrated that performs operando in‐liquid scanning dielectric microscopy measurements on functional EGOTs and carries out extensive data analysis to unravel the evolution of local electrical properties in minute detail. This paper emphasizes critical experimental considerations permitting standardized, accurate, and reproducible data acquisition. The developed approach is validated with EGOTs based on blends of organic small molecule semiconductor and insulating polymer that work as accumulation‐mode field‐effect transistors. Furthermore, the degradation of local electrical characteristics at high gate voltages is probed, which is apparently driven by the destruction of local crystalline order due to undesirable electrochemical swelling of the organic semiconducting material near the source electrode edge. The developed approach paves the way for systematic probing of EGOT‐based technologies for targeted optimization and fundamental understanding.

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Mapping the dielectric constant of a single bacterial cell at the nanoscale with scanning dielectric force volume microscopy

Abstract: A method to map the dielectric constant of non-planar samples is presented, and applied to single bacterial cells.

Cited by 15 publications

References 60 publications

Nanoscale Mapping of the Conductivity and Interfacial Capacitance of an Electrolyte‐Gated Organic Field‐Effect Transistor under Operation

Nanoscale Mapping of the Conductivity and Interfacial Capacitance of an Electrolyte‐Gated Organic Field‐Effect Transistor under Operation

Label-Free Biosensors for Laboratory-Based Diagnostics of Infections: Current Achievements and New Trends

Automated Scanning Dielectric Microscopy Toolbox for Operando Nanoscale Electrical Characterization of Electrolyte‐Gated Organic Transistors

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