Temperature compensation for measured frequency and dissipation values

Hello,

I am using the openQCM Q-1 to measure particle adsorption from liquid media. I have been performing the experiments in an air-conditioned lab, where temperature is usually controlled within 1.5 degree celsius.

While taking measurements, I have noticed that the readings follows the trend of the temperature measurements, whereby when temperature decreases, frequency decreases while dissipation increases. The temperature fluctuations are not large, typically within 1 degree celsius throughout the experiment, but sudden fluctuations (e.g. due to surrounding movement or air condition cycles) affects the frequency and dissipation values measured.

I have previously worked with the QCM200 system from Stanford Research Systems, and they had provided temperature coefficients of 8Hz/°C and 4Ω/°C for frequency and resistance, respectively (values are for AT-cut, 5MHz crystals in water under static conditions). May I know if there is a similar method that I can use to perform temperature compensation on the measured frequency and dissipation values using the openQCM Q-1 device?

I would greatly appreciate your advice regarding this matter to ensure the validity of my data. Thank you in advance for your time and assistance.

Comments

  • Hi huijeanlim,
    regarding your question, each quartz has a T-freq dependance. This is due to the variation of the wave propagation along with the quartz thickness. Anyway, it is important to underline that every single quartz has a different T behavior with respect to another one because of its intrinsic physical difference. (see the below image)






    So to give only one T coefficient can be certainly useful but in my opinion not sufficient.
    Regarding the T-freq relation, QCM sensors have a dependence well described by a 6th-degree polynomial.
    You can easily take account of this effect by experimentally build a T-freq curve with a clean sensor in your experimental environment (eg.: air, vacuum pr liquid medium).

    Once retrieved this curve (that can differ from sensor to sensor) you can subtract this effect from your experimental data.

    Below you can observe an example of T vs freq curve (red are experimental data and blue are fitted data)




    I hope this will help you.
  • Hi Raffaele,

    Thanks for your reply, I will give it a try.
  • You are welcome and thank you too!
  • Hi, we have kind of a very similar problem. We are trying to generate a similar characterization curve as the one Raffaele showed in his previous post. We are using the openQCM Q-1- shield. We were wondering how you performed that experiment because we see in our data a time lag between the temperature measured (the temperature sensor is placed on the shield?) and the frequency reading.

    Thanks for the help
  • Hi Vince90, I do not if huijeanlim will answer and how he performed the calibration. Anyway, a temporal lag can be due to the distance from the QCM sensor from the T sensor. As matter of fact each system has its proper thermal inertia. I can only say you that in a complete Q-1 device the T sensor is just 1-2 mm below the QCM sensor.
  • Hi @Vince90, I've noticed a time lag of 100s between the temperature and frequency readings in my experiments, which was consistent across many runs/different crystals. So I've simply removed this time lag by shifting the T measurements 100s forward. From there, the T-freq curves have a good R2 value of >0.99 for both the 6th degree polynomial and a linear function. In my case, I've just used the linear function to perform T compensation on my frequency data since I'm dealing with very small T fluctuations, and I am able to get R2>0.99 for the linear function. Hope this helps.
  • Great @huijeanlim ... your approach is absolutely correct!
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