Interactions at surfaces and interfaces are crucial in many fields, including environmental science, biopharmaceutical research, materials science, catalysis, and nanotechnology. The ability to detect minute changes in mass, viscoelastic properties, and interfacial phenomena can be crucial in determining the success of groundbreaking research. Understanding these interactions allows for the design of better materials and devices with tailored properties.
Quartz Crystal Microbalance with Dissipation Monitoring (QCM-D) is one of the most used techniques to quantify surface interactions with nano level mass sensitivity in real time.1 But not all QCM-D systems have similar abilities. QSense Omni stands out as the most sensitive QCM-D system on the market, pushing the boundaries of detection and resolution. This blog explores how QSense Omni redefines QCM-D performance by delivering unmatched sensitivity, enabling researchers to acquire more detailed insights than ever before.
Importance of Sensitivity in QCM-D
QCM-D technology offers real-time monitoring of molecular interactions, making it ideal for surface studies. It relies on the piezoelectric properties of a quartz crystal to measure mass changes and viscoelastic properties at the nanoscale. QCM-D measures the change in frequency and energy dissipation of a quartz crystal resonator when mass is adsorbed or desorbed from the surface, as illustrated in Figure 1.
An increase in sensitivity of the QCM-D system can enable:
- Enhanced precision in characterization of viscoelastic properties is important for soft matter applications, including hydrogels, lipid bilayers, and complex biofilms.
- Detection of lower mass changes can be essential for measuring weak interactions and detection of low-concentration analytes.
- Higher mass sensitivity can lead to better quantification of molecular-level interactions at surfaces and interfaces.
- Ultrathin layers can be characterized at higher resolution which can be crucial for studying biomolecular interactions, polymer coatings, and self-assembled monolayers.
QSense Omni
The latest QSense model, Omni, has taken mass sensitivity to the next level making it the most sensitive surface analysis tool in the current market. The remarkable improvement in signal to noise ratio combined with new smart sampling algorithms and patented temperature control of the Omni enables mass detection down to 0.24 ng/cm2. Table 1 summarizes the performance specifications of the QSense Omni.
| QSense Omni Performance Specifications | ||
| Theoretical LOD | 0.24 ng/cm2 | |
| Minimum frequency noise | 0.005 Hz | |
| Minimum mass noise | 0.08 ng/cm2 | |
| Minimum dissipation noise | 1∙10-9 | |
Several improvements in instrumentation design, liquid handling, and sensing contribute to this increase in sensitivity. Some of the key improvements include:
1. Improved Signal-to-Noise Ratio:
One of the defining features of QSense Omni is its exceptionally low noise floor. The reduction in noise levels by 4 times compared to previous models allows for the detection of even the smallest frequency and dissipation shifts, improving measurement reliability and reproducibility. QSense Omni can distinguish extremely small changes in mass with exceptional clarity, making it ideal for experiments that require ultra-sensitive measurements, such as interactions with low-abundance molecules (e.g.: protein-protein interactions,) or subtle surface changes (e.g.: lipid membrane studies).
2. Optimized Fluidics:
The QSense Omni utilizes direct injection fluidics which provides a short liquid pathway for fast, sharp and highly reproducible liquid exchange. Omni’s liquid exchange is 5 times faster compared to conventional tubing QCM-D systems. The novel design of Omni’s fluidics automatically discards sample volumes where samples might have been mixed by unwanted diffusion, leading to enhanced control of molecular concentration over sensor. This ensures precise and repeatable measurements, ideal for delicate biological assays and kinetics measurements.
3. Patented Temperature Control:
Temperature fluctuations can significantly affect measurements in QCM-D studies, causing unwarranted drift in the frequency separate detectable from mass or other surface changes. Omni’s new patented temperature control system ensures that measurements are stable and reproducible, even in environments where thermal effects are a concern. This is especially critical when studying processes like adsorption or desorption that are temperature dependent, over extended time periods, or at ultra-low concentrations. Omni achieves such fine temp control by its sophisticated internal design and multiple temperature sensors that keep the samples, sample flow paths, and sensors within the same temperature-controlled chamber.
4. Improved Sensor Mounting Mechanism:
An improved sensor mounting mechanism helps minimize mechanical vibrations and strain, ensuring that the sensors maintain a high level of precision during experiments. This contributes to the stability and accuracy of the data, especially during long-term or high-precision experiments. The sensor “mounting guide” of QSense Omni helps mount the sensor in the right position, and the “automated locking” mechanism ensures the same force is applied every time. The control mounting maintains the acoustic fingerprint of the sensor for excellent repeatability. This mechanism delivers 25 times less user-induced variations compared to other Qsense systems. The feature is particularly important for characterization of coatings applied ex-situ.
5. Smart Sampling Algorithms:
The QSense Omni utilizes a high-speed sampling algorithm, allowing it to collect up to 300 data points per second, the highest sampling rate among available QCM instruments. This enables the accurate capture of fast kinetic processes without compromising on sensitivity or resolution at such high rates.
Conclusion:
These enhancements in instrument design and smart sampling algorithms have enabled QSense Omni to be able to detect even the smallest molecular changes on surfaces, making it an incredibly powerful tool for precision research. These advances open new possibilities for research and industrial applications, especially in areas like:
- Pharmaceuticals and Drug Discovery: Detecting interactions at the molecular level in drug binding studies.
- Environmental Science: Studying small toxic molecules or detecting water contaminants at environmentally relevant concentrations.
- Biotechnology: Investigating biomolecular interactions with previously unattainable resolution.
- Materials Science: Studying very thin coatings, films, or surface modifications with better precision.
The QSense Omni is positioning itself as a leader in mass-sensitive surface analysis, surpassing other QCM-D instruments in terms of sensitivity, noise reduction, and overall performance.
References:
- Easley, A. D.; Ma, T.; Eneh, C. I.; Yun, J.; Thakur, R. M.; Lutkenhaus, J. L. A practical guide to quartz crystal microbalance with dissipation monitoring of thin polymer films. Journal of Polymer Science 2021, 60 (7), 1090–1107. https://doi.org/10.1002/pol.20210324. ↩︎
