Studying Soft Interfaces with Shear Waves: Principles and Applications of the Quartz Crystal Microbalance (QCM)

Johannsmann, Diethelm; Langhoff, Arne; Leppin, Christian

doi:10.3390/s21103490

Cited by 58 publications

(79 citation statements)

References 224 publications

(284 reference statements)

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“…The complex frequency shift, Δ f + i Δ Γ , is proportional to the area‐averaged complex amplitude of the stress exerted onto the resonator surface by the sample. The ratio of the shear stress to the transverse velocity is the “load impedance.” [ 23 ] Impedances of this kind have analogies in electricity (in which case the impedance is a voltage‐to‐current ratio rather than a stress‐to‐velocity ratio). As in electricity, there are equivalent circuits available for modeling.…”

Section: Resultsmentioning

confidence: 99%

“…The advanced QCMs (also termed “QCM‐D” for QCM with dissipation monitoring) report the resonance bandwidth in addition to the resonance frequency and they do so on a number of different overtones. [ 23 ] This added information typically is turned into an estimate of the sample's softness.…”

Section: The Qcm As An Instrument To Detect and Quantify Foulingmentioning

confidence: 99%

“…The ratio of the shear stress to the transverse velocity is the "load impedance." [23] Impedances of this kind have analogies in electricity (in which case the impedance is a voltage-to-current ratio rather than a stress-to-velocity ratio). As in electricity, there are equivalent circuits available for modeling.…”

Section: Formation Of Large Amounts Of Fouling Materialsmentioning

confidence: 99%

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Fouling Pathways in Emulsion Polymerization Differentiated with a Quartz Crystal Microbalance (QCM) Integrated into the Reactor Wall

Böttcher

Petri

Langhoff

et al. 2022

Macro Reaction Engineering

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Emulsion polymerization fouling at hot interfaces is studied in situ, making use of a quartz crystal microbalance with dissipation monitoring (QCM-D). The resonator crystal is heated with a ring-shaped thermal pad from the back, turning it into a plate with elevated temperature. Configured to be one of the walls of a small reactor for emulsion polymerization, this resonator is prone to heat-transfer fouling, similar to regular heated parts of process equipment. The fouling kinetics is readily quantified with this QCM. During polymerization at constant temperature (80 °C), some deposition is always observed. However, a film with a thickness of less than 1 𝝁m (determined gravimetrically with the QCM) is sometimes found, which stabilizes the surface against the deposition of much thicker layers. When reaction fouling proceeds directly to thick deposits, a small increase in resonance bandwidth often occurs a few minutes prior to the main transition, presumably caused by coagulum formed in the bulk making first contact with the surface. Furthermore, particle fouling is studied with temperature ramps on nonreactive dispersions. Fouling, if present, is readily observed.

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Section: Resultsmentioning

confidence: 99%

Section: The Qcm As An Instrument To Detect and Quantify Foulingmentioning

confidence: 99%

Section: Formation Of Large Amounts Of Fouling Materialsmentioning

confidence: 99%

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Fouling Pathways in Emulsion Polymerization Differentiated with a Quartz Crystal Microbalance (QCM) Integrated into the Reactor Wall

Böttcher

Petri

Langhoff

et al. 2022

Macro Reaction Engineering

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“…Last but not least, the transition between regimes III and IV is likely defined by the limited sensing depth of QCM-D. The sensing depth in water (as well as ultrasoft HA films) is on the order of a few 100 nm 69 , 70 which is rather close to the radius of gyration of the largest HA chains ( R g ≈ 75 nm for HA 838 kDa); therefore, even with only moderate chain stretching the HA brush thickness can readily exceed the QCM-D sensing depth. Indeed, we have previously reported brushes made from the largest HA chains to reach thickness values in the range of hundreds of nanometres and to be very soft, explaining why they can give rise to very modest negative normalised frequency shifts (in the range of few Hz; see Fig.…”

Section: Discussionmentioning

confidence: 99%

A quartz crystal microbalance method to quantify the size of hyaluronan and other glycosaminoglycans on surfaces

Srimasorn

Souter

Green

et al. 2022

Sci Rep

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Hyaluronan (HA) is a major component of peri- and extra-cellular matrices and plays important roles in many biological processes such as cell adhesion, proliferation and migration. The abundance, size distribution and presentation of HA dictate its biological effects and are also useful indicators of pathologies and disease progression. Methods to assess the molecular mass of free-floating HA and other glycosaminoglycans (GAGs) are well established. In many biological and technological settings, however, GAGs are displayed on surfaces, and methods to obtain the size of surface-attached GAGs are lacking. Here, we present a method to size HA that is end-attached to surfaces. The method is based on the quartz crystal microbalance with dissipation monitoring (QCM-D) and exploits that the softness and thickness of films of grafted HA increase with HA size. These two quantities are sensitively reflected by the ratio of the dissipation shift (ΔD) and the negative frequency shift (− Δf) measured by QCM-D upon the formation of HA films. Using a series of size-defined HA preparations, ranging in size from ~ 2 kDa tetrasaccharides to ~ 1 MDa polysaccharides, we establish a monotonic yet non-linear standard curve of the ΔD/ − Δf ratio as a function of HA size, which reflects the distinct conformations adopted by grafted HA chains depending on their size and surface coverage. We demonstrate that the standard curve can be used to determine the mean size of HA, as well as other GAGs, such as chondroitin sulfate and heparan sulfate, of preparations of previously unknown size in the range from 1 to 500 kDa, with a resolution of better than 10%. For polydisperse samples, our analysis shows that the process of surface-grafting preferentially selects smaller GAG chains, and thus reduces the average size of GAGs that are immobilised on surfaces comparative to the original solution sample. Our results establish a quantitative method to size HA and other GAGs grafted on surfaces, and also highlight the importance of sizing GAGs directly on surfaces. The method should be useful for the development and quality control of GAG-based surface coatings in a wide range of research areas, from molecular interaction analysis to biomaterials coatings.

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“…The QCM sensor based on AT-cut quartz crystals can be used in liquid medium [2,3] and passive interrogation at resonance is currently the basic method [4][5][6]. Reviews on the QCM electronic interfaces can be found in [7][8][9]. QCM sensors are now widely used as biosensors [10][11][12] and have been combined with scanning force microscopy, optical reflectometry, electrochemistry, and other interface analysis tools.…”

Section: Introductionmentioning

confidence: 99%

Quartz Crystal Microbalance with Impedance Analysis Based on Virtual Instruments: Experimental Study

Burda

2022

Sensors

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The impedance quartz crystal microbalance (QCMI) is a versatile and simple method for making accurate measurements of the QCM sensor electrical parameters. The QCM sensor provides access to the physical parameters of the sample beyond the mass per unit area by measuring the dissipation factor, or another equivalent, ensuring a detailed analysis of the surface. By establishing a cooperative relationship between custom software and modular configurable hardware we obtain a user-defined measurement system that is called a virtual instrument. This paper aims primarily to improve and adapt existing concepts to new electronics technologies to obtain a fast and accurate virtual impedance analyzer (VIA). The second is the implementation of a VIA by software to cover a wide range of measurements for the impedance of the QCM sensor, followed by the calculation of the value of lumped electrical elements in real time. A method for software compensation of the parallel and stray capacitance is also described. The development of a compact VIA with a decent measurement rate (192 frequency points per second) aims, in the next development steps, to create an accurate impedance analyzer for QCM sensors. The experimental results show the good working capacity of QCMI based on VIA.

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Studying Soft Interfaces with Shear Waves: Principles and Applications of the Quartz Crystal Microbalance (QCM)

Cited by 58 publications

References 224 publications

Fouling Pathways in Emulsion Polymerization Differentiated with a Quartz Crystal Microbalance (QCM) Integrated into the Reactor Wall

Fouling Pathways in Emulsion Polymerization Differentiated with a Quartz Crystal Microbalance (QCM) Integrated into the Reactor Wall

A quartz crystal microbalance method to quantify the size of hyaluronan and other glycosaminoglycans on surfaces

Quartz Crystal Microbalance with Impedance Analysis Based on Virtual Instruments: Experimental Study

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