QCM-D ease-of-use product design eliminates the need for a superuser
Jennie Ringberg May 23, ’23 > 11 min

QCM-D ease-of-use product design eliminates the need for a superuser

A challenge with advanced scientific equipment, such as QCM-D, is that an expert user can be required to generate high quality data. To enable more users to benefit from the QCM-D technology, we developed QSense Omni - QSense 4th generation platform which is designed to lower the knowledge barrier needed to produce high quality QCM-D data. 

The "super user trap" - expensive investment in knowledge that is impossible to transfer

A challenge with advanced scientific equipment is that expert user skills can be required to generate high quality data, and QCM-D is no exception. QCM-D is a highly sensitive technology measuring surface interaction on a nanoscale with high precision. However, this also makes the technology sensitive to external factors and unwanted variations due to differences in manual handling, cleaning procedures etc. It can require long experience and special expertise to develop reliable and reproducible data. We have noted that spending time with our instruments, and running lots of experiments, the end-user will over time acquire a fundamental understanding of the working principles of the QCM-D technology and develop an intuition for what aspects of the different measurement steps that are critical and have a major impact on the quality of the produced data. Learning how to interpret the, sometimes subtle, signs indicating that something is not quite right, the superuser will develop a special touch which may take many years to master, and which is difficult, if not to say impossible, to transfer to another user. In fact, it is not rare that measurements performed by a novice user, meticulously following the QCM-D best-practice instructions, may turn out very different from those performed by the expert user even though the measurement preparation, setup and performance seemingly was identical in the two cases.

How to avoid the superuser requirement and lower the QCM-D usability barrier

One way to overcome the expert user requirement could be to de-couple as much as possible of the critical measurement setup- and execution steps from the instrument operator, i.e., to make the measurement operator-independent by transferring the critical key procedures, checks, and decisions to the instrument. The instrument is better equipped to identify subtle disturbances, and it can make decisions based on identical criteria every time. Additionally, the instrument user interface could be so intuitive, and guiding the user in such an efficient way, that an expert user would not be needed. Not only will this approach reduce the risk of investing lots of time and resources in one, or a few, QCM-D technology knowledge bearers, but in organizations where one or more dedicated users are still preferred, the start-up training of these individuals will be swift, and more users could easily be added if/when desired without compromising the data quality.

Lower the usability barrier by implementing a user-independent QCM-D platform

One of the key ambitions with QSense 4th generation QCM-D platform was to lower the knowledge barrier needed to produce high quality QCM-D data. We wanted more users to be able to access and benefit from the information provided by QCM-D without having to invest years and years in training to gain sufficient experience, and without wasting time and resources on measurements with bad setup conditions resulting in low quality data. To realize this ambition, we have taken automation and user independence to the next level. The ease-of-use and automation initiative help and guide the user throughout the whole process, spanning measurement setup, execution, and post-measurement.

Product design and features implemented to realize a user-independent QCM-D platform

Below are listed some of the features that were implemented to address the superuser requirements and reduce the need of an expert user:

  1. Automated quality checks
    The knowledge, expertise and fingertip feel of the superuser have been transferred to the instrument and software. This means that there is no need to worry about the set-up or starting an experiment with incorrect or unstable temperature or with set-up conditions where the instrument cannot capture all the data required for optimal quantitative analysis. QSense Omni will make sure that the measurement is started with the correct and optimal conditions. Each sensor and channel are automatically checked to make sure that the set temperature is reached, that all harmonics are found, that the signals lie within expected values and that the baseline is stable. This happens automatically in the background, but all information is easily accessible in the software and ready for inspection if desired. The data in Fig. 1 was collected after the preceding automatic quality checks, a great foundation for a successful measurement.


    Figure 1. Frequency shifts, shown in blue, and dissipation shifts, shown in red, for an antibody assay build-up using QSense Omni: immobilization of coupling molecules, streptavidin, and biotinylated protein A, followed by capturing of anti-BSA and antigen binding, BSA.

  2. Automated and controlled sensor mounting and locking
    Sensor mounting can be tricky, but in QSense Omni, a sensor mounting guide enhances the success rate of the sensor mounting. The guide helps place the sensor in the perfect position to minimize signal disturbance, and the risk of cracking the sensor upon mounting is essentially eliminated. The instrument uses well-defined force to connect the sample holder and the sensor holder which results in higher reproducibility.

    In addition to the risk of cracking the sensor when manually mounting the sensor, the variation in signal due to remounting of the sensor is a limitation when it comes to measuring before and after ex-situ coating and makes it difficult to determine the mass/thickness of the ex-situ coated film on the sensor. This variation has been greatly reduced in QSense Omni compared to the previous QSense platforms, Fig. 2. Correct and repeatable sensor and sensor holder mounting allow for more successful experiments.

    Fig 1

    Figure 2. A graph showing the variation in frequency when remounting the sensor in the different QSense instruments, Omni, Pro and Analyzer. Mounting and remounting the sensor multiple times, there is a variation of 50 Hz in the Analyzer. For QSense Pro, the corresponding error is 28 Hz whereas that number is as low as 2 Hz for QSense Omni. This low variation increases the possibilities of measuring coatings applied ex-situ.

  3. Automated sample handling
    Manual handling of the experimental components is time-consuming as it forces the user to be in the lab. It is also a source of error and unwanted variations. QSense Omni is equipped with automated sample handling which means there is no manual stopping of the pump and switching of tubing between samples. It also means that sample injection is controlled and repeatable. The result is less user dependence, minimal hands-on interaction, saved time and increased reproducibility, Fig. 3.

    Fig 4 MOD

    Figure 3. A graph showing a triplicate of frequency changes over time. Each trace showing the adsorption of Poly-L-Lysine (PLL) to silica surface, QSX 303.

  4. Automated cleaning
    Cleanliness is key when working with QCM-D and QSense Omni has integrated cleaning procedures in place to secure and simplify cleaning of the instrument. Separate cleaning programs can also be tailor-made by the user for specific needs. This will reduce the risk of cross-contamination, cross-over effects and minimize user introduced variations and error, thus increasing reproducibility, Fig. 3, and reliability of data.


Concluding remarks

QCM-D is an advanced scientific technology that can measure surface interactions with high precision on a nanoscale. However, due to its sensitivity to external factors and variations in, for example, manual handling and cleaning procedures, it can require “super-user skills”, i.e., specialized knowledge and experience to generate reliable and reproducible data. To overcome this challenge and enable more users to benefit from the QCM-D technology, we have developed QSense 4th generation QCM-D platform, a sophisticated instrument designed to minimize the user knowledge required to produce high-quality data.

Download the technical whitepaper to learn more about QSense Omni design and features.


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