Quartz Crystal MicroBalance (QCM) - Revision history

E0309214 at 04:42, 23 April 2024

2024-04-23T04:42:17Z

← Older revision		Revision as of 12:42, 23 April 2024
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	==Working Principle==		==Working Principle==
	[[File:AT and BT cut.png\|340px\|thumb\|right\|Figure 1: Orientation of AT- and BT- cut crystals]]The working principle behind the QCM is based on the piezoelectric effect. The piezoelectric effect is the generation of electric charges by a crystalline material upon subjecting it to stress.~~[1]~~ An oscillating electric field applied across the device induces an acoustic wave that propagates through the crystal and meets minimum impedance when the device's thickness is a half-integer multiple of the wavelength of the acoustic wave.~~[2]~~ It is a shear mode device in which the acoustic wave propagates in a direction perpendicular to the crystal surface.~~[3]~~ Therefore, crystals cut in specific crystal axes have to be used to utilize the shear mode. A resonant oscillation in the crystal is achieved by putting the crystal in an oscillation circuit where the electrical and mechanical oscillations are close to the fundamental frequency of the crystal. Changes to the mass of the crystal would result in a proportional change in its natural frequency according to the Sauerbrey equation~~[4]~~		[[File:AT and BT cut.png\|340px\|thumb\|right\|Figure 1: Orientation of AT- and BT- cut crystals]]The working principle behind the QCM is based on the piezoelectric effect. The piezoelectric effect is the generation of electric charges by a crystalline material upon subjecting it to stress.<ref>Meissner A (1927) € Uber piezoelectrische Krystalle bei Hochfrequenz. Z Tech Phys 8:74</ref> An oscillating electric field applied across the device induces an acoustic wave that propagates through the crystal and meets minimum impedance when the device's thickness is a half-integer multiple of the wavelength of the acoustic wave.<ref>O’Sullivan, C. K., & Guilbault, G. G. (1999). Commercial quartz crystal microbalances – theory and applications. Biosensors and Bioelectronics, 14(8), 663–670.</ref> It is a shear mode device in which the acoustic wave propagates in a direction perpendicular to the crystal surface.<ref>Ebersole, R., Miller, J., Moran, J., & Ward, M. (1990). PZ quartz sensors for use in clinical analysis. J. Am. Chem. Soc, 112, 3239.</ref> Therefore, crystals cut in specific crystal axes have to be used to utilize the shear mode. A resonant oscillation in the crystal is achieved by putting the crystal in an oscillation circuit where the electrical and mechanical oscillations are close to the fundamental frequency of the crystal. Changes to the mass of the crystal would result in a proportional change in its natural frequency according to the Sauerbrey equation<ref>Sauerbrey, G. (1959). Verwendung von Schwingquarzen zur Wägung dünner Schichten und zur Mikrowägung. Zeitschrift für Physik, 155(2), 206–222.</ref>

	<math>		<math>
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	The waveform seen on the oscilloscope is observed to be periodic and looks like a square-wave oscillation. There seem to be additional peaks periodically formed as well, which could likely come from circuit impedance mismatches. Mismatches in impedance between different components or sections of a circuit can cause signal reflections and distortions, leading to additional peaks in the waveform. We would have to adjust the values of the capacitors and resistors.		The waveform seen on the oscilloscope is observed to be periodic and looks like a square-wave oscillation. There seem to be additional peaks periodically formed as well, which could likely come from circuit impedance mismatches. Mismatches in impedance between different components or sections of a circuit can cause signal reflections and distortions, leading to additional peaks in the waveform. We would have to adjust the values of the capacitors and resistors.

	Then, we replace the 10Mhz crystal oscillator with the AT-cut crystal. Although we managed to obtain the frequency signal generated by the AT-cut crystal, the surface of the crystal is very sensitive such that waving your hands near the oscillator causes the waveform to change. To make the signal more stable, we construct another circuit design similar to the Colpitts oscillator.~~[5]~~ One of the advantages of using this layout is that relatively low phase noise can be achieved, making them suitable for applications requiring stable and low-noise oscillation.		Then, we replace the 10Mhz crystal oscillator with the AT-cut crystal. Although we managed to obtain the frequency signal generated by the AT-cut crystal, the surface of the crystal is very sensitive such that waving your hands near the oscillator causes the waveform to change. To make the signal more stable, we construct another circuit design similar to the Colpitts oscillator.<ref>US 1624537, Colpitts, Edwin H., "Oscillation generator", published 1 February 1918, issued 12 April 1927</ref> One of the advantages of using this layout is that relatively low phase noise can be achieved, making them suitable for applications requiring stable and low-noise oscillation.
	<br clear=all>		<br clear=all>
	----		----
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	==Potential Improvements and Conclusion==		==Potential Improvements and Conclusion==
	Some better models describe the relationship between frequency change and mass adsorbed where we consider the added mass to be viscoelastic. The Sauerbrey equation fails to describe viscoelastic films on the quartz oscillator as the condition where the added mass is rigidly bound is not adhered to. This model is called the QCM-D, where D refers to the energy dissipation by the film. This technique is prevalent in the fields of lipids, proteins, nanoparticles, etc. ~~[6]~~ However, this requires the use of liquid media. <br />		Some better models describe the relationship between frequency change and mass adsorbed where we consider the added mass to be viscoelastic. The Sauerbrey equation fails to describe viscoelastic films on the quartz oscillator as the condition where the added mass is rigidly bound is not adhered to. This model is called the QCM-D, where D refers to the energy dissipation by the film. This technique is prevalent in the fields of lipids, proteins, nanoparticles, etc.<ref>Chen, Q., Xu, S., Liu, Q., Masliyah, J., & Xu, Z. (2016). QCM-D study of nanoparticle interactions. Advances in Colloid and Interface Science, 233, 94–114.</ref> However, this requires the use of liquid media. <br />

	To conclude, we managed to detect the quartz crystal oscillation with a simple circuit design. Changes in resonance frequency due to added mass can also be detected, but the margin of error is too large for it to be usable for research purposes. Future improvements to this experiment can be done by adopting energy dissipation within our considerations.		To conclude, we managed to detect the quartz crystal oscillation with a simple circuit design. Changes in resonance frequency due to added mass can also be detected, but the margin of error is too large for it to be usable for research purposes. Future improvements to this experiment can be done by adopting energy dissipation within our considerations.
	----		----
	==References==		==References==
	~~# Meissner A (1927) € Uber piezoelectrische Krystalle bei Hochfrequenz. Z Tech Phys 8:74~~		<references />
	~~# O’Sullivan, C. K., & Guilbault, G. G. (1999). Commercial quartz crystal microbalances – theory and applications. Biosensors and Bioelectronics, 14(8), 663–670.~~
	~~# Ebersole, R., Miller, J., Moran, J., & Ward, M. (1990). PZ quartz sensors for use in clinical analysis. J. Am. Chem. Soc, 112, 3239.~~
	~~# Sauerbrey, G. (1959). Verwendung von Schwingquarzen zur Wägung dünner Schichten und zur Mikrowägung. Zeitschrift für Physik, 155(2), 206–222.~~
	~~# US 1624537, Colpitts, Edwin H., "Oscillation generator", published 1 February 1918, issued 12 April 1927~~
	~~# Chen, Q., Xu, S., Liu, Q., Masliyah, J., & Xu, Z. (2016). QCM-D study of nanoparticle interactions. Advances in Colloid and Interface Science, 233, 94–114.~~

E0309214: /* References */

2024-04-23T04:37:55Z

References

← Older revision		Revision as of 12:37, 23 April 2024
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	# Ebersole, R., Miller, J., Moran, J., & Ward, M. (1990). PZ quartz sensors for use in clinical analysis. J. Am. Chem. Soc, 112, 3239.		# Ebersole, R., Miller, J., Moran, J., & Ward, M. (1990). PZ quartz sensors for use in clinical analysis. J. Am. Chem. Soc, 112, 3239.
	# Sauerbrey, G. (1959). Verwendung von Schwingquarzen zur Wägung dünner Schichten und zur Mikrowägung. Zeitschrift für Physik, 155(2), 206–222.		# Sauerbrey, G. (1959). Verwendung von Schwingquarzen zur Wägung dünner Schichten und zur Mikrowägung. Zeitschrift für Physik, 155(2), 206–222.
	# US 1624537, Colpitts, Edwin H., "Oscillation generator", published 1 February 1918, issued 12 April 1927		# US 1624537, Colpitts, Edwin H., "Oscillation generator", published 1 February 1918, issued 12 April 1927
			# Chen, Q., Xu, S., Liu, Q., Masliyah, J., & Xu, Z. (2016). QCM-D study of nanoparticle interactions. Advances in Colloid and Interface Science, 233, 94–114.

E0309214: /* Second Measurement */

2024-04-23T04:37:20Z

Second Measurement

E0309214: /* Second Set-Up */

2024-04-23T04:33:52Z

Second Set-Up

← Older revision		Revision as of 12:33, 23 April 2024
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	==Second Set-Up==		==Second Set-Up==
	The circuit design and the actual circuit are shown in ~~Figure ()~~. 2N2222 bipolar junction transistors were used with a combination of capacitors and resistors. The purpose of the transistor is to amplify the voltage across the resonant circuit and stabilize the oscillations through a feedback loop. A DC power supply of 9V is applied across the circuit and an oscilloscope is connected to observe the waveform. Figure () shows the waveform, which seems to be a superposition of a square wave and another periodic signal which could be due to the aforementioned circuit impedance mismatches.		The circuit design and the actual circuit are shown in Figures 7 and 8. 2N2222 bipolar junction transistors were used with a combination of capacitors and resistors. The purpose of the transistor is to amplify the voltage across the resonant circuit and stabilize the oscillations through a feedback loop. A DC power supply of 9V is applied across the circuit and an oscilloscope is connected to observe the waveform. Figure 8 shows the waveform, which seems to be a superposition of a square wave and another periodic signal which could be due to the aforementioned circuit impedance mismatches.
	[[File:Circuit diagram 2nd.png\|340px\|thumb\|~~right~~\|Circuit Diagram for 2nd setup]]		[[File:Circuit diagram 2nd.png\|340px\|thumb\|left\|Figure 7: Circuit Diagram for 2nd setup]]
	[[File:2nd setup.jpeg\|340px\|thumb\|~~left~~\|2nd Experimental setup]]		[[File:2nd setup.jpeg\|340px\|thumb\|right\|Figure 8: 2nd Experimental setup]]
	<br clear=all>		<br clear=all>
	We use the Anritsu MS2711D Spectrum Master to look for the resonance frequencies as a cross-reference to the frequency counter measurement. In Figure (), the resonance frequency of the piezoelectric quartz oscillator and its higher-order harmonics are shown. ~~[insert resonance frequency narrow, wide scan of frequency]~~ From the wide scan, we can see that the zeroth-order overtone occurs at approximately 6Mhz, and the higher-order harmonics occur in multiple integers of 6MHz.		We use the Anritsu MS2711D Spectrum Master to look for the resonance frequencies as a cross-reference to the frequency counter measurement. In Figure 9, the resonance frequency of the piezoelectric quartz oscillator and its higher-order harmonics are shown. From the wide scan, we can see that the zeroth-order overtone occurs at approximately 6Mhz, and the higher-order harmonics occur in multiple integers of 6MHz.
	[[File:Wide scan.jpeg\|340px\|thumb\|right\|Spectral survey scan using the Anritsu MS2711D Spectrum Master]]		[[File:Wide scan.jpeg\|340px\|thumb\|right\|Figure 9: Spectral survey scan using the Anritsu MS2711D Spectrum Master]]
	[[File:Narrow scan.jpeg\|340px\|thumb\|left\|Spectral narrow scan using the Anritsu MS2711D Spectrum Master]]		[[File:Narrow scan.jpeg\|340px\|thumb\|left\|Figure 10: Spectral narrow scan using the Anritsu MS2711D Spectrum Master]]
	<br clear=all>		<br clear=all>
	----		----

	==Second Measurement==		==Second Measurement==
	The procedure for the frequency counter measurements is the same as that of the 10MHz crystal oscillator. The fundamental resonant frequency is measured to be 5.986804MHz. Using this as the reference resonance frequency, we can now test its effectiveness in mass measurements with the Sauerbrey equation.		The procedure for the frequency counter measurements is the same as that of the 10MHz crystal oscillator. The fundamental resonant frequency is measured to be 5.986804MHz. Using this as the reference resonance frequency, we can now test its effectiveness in mass measurements with the Sauerbrey equation.

E0309214: /* Measurements */

2024-04-23T04:31:56Z

Measurements

← Older revision		Revision as of 12:31, 23 April 2024
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	==Measurements==		==Measurements==
	[[File:1st setup waveform.jpeg\|340px\|thumb\|right\|Waveform observed with an oscilloscope using the CMAC CK q5 crystal oscillator]]		[[File:1st setup waveform.jpeg\|340px\|thumb\|right\|Figure 5: Waveform observed with an oscilloscope using the CMAC CK q5 crystal oscillator]]
	[[File:10mhz waveform.jpeg\|340px\|thumb\|right\|Waveform observed with an oscilloscope using the AT-cut quartz crystal]]		[[File:10mhz waveform.jpeg\|340px\|thumb\|right\|Figure 6: Waveform observed with an oscilloscope using the AT-cut quartz crystal]]
	A DC power supply of 5V is given and an oscilloscope is connected to see the signal's waveform. A frequency counter is connected to the electrical circuit and communicated to my computer via the Arduino Integrated Development Environment. The frequency is measured for 10 seconds 10 times to get an average. Eventually, a resonant frequency of 10.000001Mhz is recorded, which is very close to the 10Mhz value that was provided by the manufacturer.		A DC power supply of 5V is given and an oscilloscope is connected to see the signal's waveform. A frequency counter is connected to the electrical circuit and communicated to my computer via the Arduino Integrated Development Environment. The frequency is measured for 10 seconds 10 times to get an average. Eventually, a resonant frequency of 10.000001Mhz is recorded, which is very close to the 10Mhz value that was provided by the manufacturer.

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	----		----

	==Second Set-Up==		==Second Set-Up==
	The circuit design and the actual circuit are shown in Figure (). 2N2222 bipolar junction transistors were used with a combination of capacitors and resistors. The purpose of the transistor is to amplify the voltage across the resonant circuit and stabilize the oscillations through a feedback loop. A DC power supply of 9V is applied across the circuit and an oscilloscope is connected to observe the waveform. Figure () shows the waveform, which seems to be a superposition of a square wave and another periodic signal which could be due to the aforementioned circuit impedance mismatches.		The circuit design and the actual circuit are shown in Figure (). 2N2222 bipolar junction transistors were used with a combination of capacitors and resistors. The purpose of the transistor is to amplify the voltage across the resonant circuit and stabilize the oscillations through a feedback loop. A DC power supply of 9V is applied across the circuit and an oscilloscope is connected to observe the waveform. Figure () shows the waveform, which seems to be a superposition of a square wave and another periodic signal which could be due to the aforementioned circuit impedance mismatches.

E0309214: /* Setup */

2024-04-23T04:31:17Z

Setup

← Older revision		Revision as of 12:31, 23 April 2024
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	==Setup==		==Setup==
	The typical QCM set-up of piezoelectric quartz crystal microbalance is shown in Figure ().		The typical QCM set-up of piezoelectric quartz crystal microbalance is shown in Figure 2.
	The oscillator circuit is connected to the power supply and sample stage mount where the piezoelectric quartz crystal is. We can determine the resonance frequency of the quartz crystal using an oscilloscope, frequency counter, or spectrum analyzer.		The oscillator circuit is connected to the power supply and sample stage mount where the piezoelectric quartz crystal is. We can determine the resonance frequency of the quartz crystal using an oscilloscope, frequency counter, or spectrum analyzer.

	To determine the feasibility of this QCM project, we built a simple oscillating circuit as a foundation to test if we can detect the resonance frequency of the quartz crystal. This also serves as a time buffer while waiting for the AT-cut quartz to be delivered. Figures () and () show the electrical circuit diagram and its implementation on a breadboard.		To determine the feasibility of this QCM project, we built a simple oscillating circuit as a foundation to test if we can detect the resonance frequency of the quartz crystal. This also serves as a time buffer while waiting for the AT-cut quartz to be delivered. Figures 3 and 4 show the electrical circuit diagram and its implementation on a breadboard respectively.

	As the electrical current generated from the oscillation of the quartz crystal is an alternating current due to the piezoelectric effect, we employ the usage of logic gates called inverters to convert DC to AC for readout. Adding a resistor to the circuit allows for the control of the potential difference across the inverter. In this oscillating circuit, we use a 14-pin integrated circuit and measure the resonant frequency of a CMAC CK q5 crystal oscillator.		As the electrical current generated from the oscillation of the quartz crystal is an alternating current due to the piezoelectric effect, we employ the usage of logic gates called inverters to convert DC to AC for readout. Adding a resistor to the circuit allows for the control of the potential difference across the inverter. In this oscillating circuit, we use a 14-pin integrated circuit and measure the resonant frequency of a CMAC CK q5 crystal oscillator.
	[[File:Circuit diagram 1st.png\|340px\|thumb\|left\|Circuit Diagram]]		[[File:Circuit diagram 1st.png\|340px\|thumb\|left\|Figure 3: Circuit Diagram]]
	[[File:Typical setup.png\|340px\|thumb\|right\|Typical Setup for a QCM measurement]]		[[File:Typical setup.png\|340px\|thumb\|right\|Figure 2: Typical Setup for a QCM measurement]]
	[[File:1st setup.jpeg\|340px\|thumb\|right\|Experimental Setup]]		[[File:1st setup.jpeg\|340px\|thumb\|right\|Figure 4: Experimental Setup]]
	<br clear=all>		<br clear=all>
	----		----

	==Measurements==		==Measurements==
	[[File:1st setup waveform.jpeg\|340px\|thumb\|right\|Waveform observed with an oscilloscope using the CMAC CK q5 crystal oscillator]]		[[File:1st setup waveform.jpeg\|340px\|thumb\|right\|Waveform observed with an oscilloscope using the CMAC CK q5 crystal oscillator]]

E0309214: /* Working Principle */

2024-04-23T04:30:17Z

Working Principle

← Older revision		Revision as of 12:30, 23 April 2024
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	----		----
	==Working Principle==		==Working Principle==
	[[File:AT and BT cut.png\|340px\|thumb\|right\|Orientation of AT- and BT- cut crystals]]The working principle behind the QCM is based on the piezoelectric effect. The piezoelectric effect is the generation of electric charges by a crystalline material upon subjecting it to stress.[1] An oscillating electric field applied across the device induces an acoustic wave that propagates through the crystal and meets minimum impedance when the device's thickness is a half-integer multiple of the wavelength of the acoustic wave.[2] It is a shear mode device in which the acoustic wave propagates in a direction perpendicular to the crystal surface.[3] Therefore, crystals cut in specific crystal axes have to be used to utilize the shear mode. A resonant oscillation in the crystal is achieved by putting the crystal in an oscillation circuit where the electrical and mechanical oscillations are close to the fundamental frequency of the crystal. Changes to the mass of the crystal would result in a proportional change in its natural frequency according to the Sauerbrey equation[4]		[[File:AT and BT cut.png\|340px\|thumb\|right\|Figure 1: Orientation of AT- and BT- cut crystals]]The working principle behind the QCM is based on the piezoelectric effect. The piezoelectric effect is the generation of electric charges by a crystalline material upon subjecting it to stress.[1] An oscillating electric field applied across the device induces an acoustic wave that propagates through the crystal and meets minimum impedance when the device's thickness is a half-integer multiple of the wavelength of the acoustic wave.[2] It is a shear mode device in which the acoustic wave propagates in a direction perpendicular to the crystal surface.[3] Therefore, crystals cut in specific crystal axes have to be used to utilize the shear mode. A resonant oscillation in the crystal is achieved by putting the crystal in an oscillation circuit where the electrical and mechanical oscillations are close to the fundamental frequency of the crystal. Changes to the mass of the crystal would result in a proportional change in its natural frequency according to the Sauerbrey equation[4]

	<math>		<math>
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	<br clear=all>		<br clear=all>
	----		----

	==Setup==		==Setup==
	The typical QCM set-up of piezoelectric quartz crystal microbalance is shown in Figure ().		The typical QCM set-up of piezoelectric quartz crystal microbalance is shown in Figure ().

E0309214: /* Second Measurement */

2024-04-23T04:28:51Z

Second Measurement

← Older revision		Revision as of 12:28, 23 April 2024
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	==Second Measurement==		==Second Measurement==
	The procedure for the frequency counter measurements is the same as that of the 10MHz crystal oscillator. The fundamental resonant frequency is measured to be 5.986804MHz. Using this as the reference resonance frequency, we can now test its effectiveness in mass measurements with the Sauerbrey equation. <br />		The procedure for the frequency counter measurements is the same as that of the 10MHz crystal oscillator. The fundamental resonant frequency is measured to be 5.986804MHz. Using this as the reference resonance frequency, we can now test its effectiveness in mass measurements with the Sauerbrey equation.
			[[File:Permanent marker.jpeg\|340px\|thumb\|left\|Depiction of how ink was placed on the quartz crystal plate]]
	Firstly, a permanent marker is used where we dot the center of the quartz crystal shown in Figure (). [insert permanent marker ink] Initially, there was no signal shown in Figure (). [Explain why~~, insert no spectral signature for ink~~]However, increasing the DC supply voltage sufficiently allows the fundamental mode to be observed as shown in Figure (). ~~[insert increase dc power supply]~~ We repeated the frequency counter measurements and found the new resonance frequency to be 5.984613MHz.		[[File:Ink no signal.jpeg\|340px\|thumb\|right\|No spectral signatures from measurement]]
			<br clear=all>
	To test the mass limit of this setup, a small Blu Tack weighing 2.1 grams is placed on the center of the oscillator. A new oscillator is used so that the dried ink does not interfere with the measurement. The Spectrum Master did not record any spectral features, which suggests that the oscillation of the crystal is too damped to be detected and that the gain is insufficient. [insert no spectral signature for blu tack] Increasing the DC power supply to 18V is inadequate to produce a spectral feature. For safety purposes, this will be the limit that we shall test.		[[File:Increase power.jpeg\|340px\|thumb\|right\|Increasing DC power supply shows a fundamental mode of resonance]]
			Firstly, a permanent marker is used where we dot the center of the quartz crystal shown in Figure (). [insert permanent marker ink] Initially, there was no signal shown in Figure (). [Explain why] However, increasing the DC supply voltage sufficiently allows the fundamental mode to be observed as shown in Figure (). We repeated the frequency counter measurements and found the new resonance frequency to be 5.984613MHz.

			To test the mass limit of this setup, a small Blu Tack weighing 2.1 grams is placed on the center of the oscillator. A new oscillator is used so that the dried ink does not interfere with the measurement. The Spectrum Master did not record any spectral features, which suggests that the oscillation of the crystal is too damped to be detected and that the gain is insufficient. Increasing the DC power supply to 18V is inadequate to produce a spectral feature. For safety purposes, this will be the limit that we shall test.
			[[File:Blu tack.jpeg\|340px\|thumb\|left\|Depiction of how Blu tack was placed on the quartz crystal plate]]
			[[File:Blu tack no signal.jpeg\|340px\|thumb\|right\|No spectral signatures from measurement]]
			<br clear=all>
	Based on the Sauerbrey equation, the decrease in resonance frequency of 2191Hz corresponds to an increase in mass of 969 micrograms. This value is derived by using the following:		Based on the Sauerbrey equation, the decrease in resonance frequency of 2191Hz corresponds to an increase in mass of 969 micrograms. This value is derived by using the following:
	* thickness of quartz crystal plate <math> t_q = 1 </math> mm		* thickness of quartz crystal plate <math> t_q = 1 </math> mm
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	Based on these conditions, the second and third conditions are not fulfilled.		Based on these conditions, the second and third conditions are not fulfilled.
	----		----

	==Potential Improvements and Conclusion==		==Potential Improvements and Conclusion==
	Some better models describe the relationship between frequency change and mass adsorbed where we consider the added mass to be viscoelastic. The Sauerbrey equation fails to describe viscoelastic films on the quartz oscillator as the condition where the added mass is rigidly bound is not adhered to. This model is called the QCM-D, where D refers to the energy dissipation by the film. This technique is prevalent in the fields of lipids, proteins, nanoparticles, etc. [6] However, this requires the use of liquid media. <br />		Some better models describe the relationship between frequency change and mass adsorbed where we consider the added mass to be viscoelastic. The Sauerbrey equation fails to describe viscoelastic films on the quartz oscillator as the condition where the added mass is rigidly bound is not adhered to. This model is called the QCM-D, where D refers to the energy dissipation by the film. This technique is prevalent in the fields of lipids, proteins, nanoparticles, etc. [6] However, this requires the use of liquid media. <br />

E0309214 at 04:20, 23 April 2024

2024-04-23T04:20:31Z

← Older revision		Revision as of 12:20, 23 April 2024
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	Then, we replace the 10Mhz crystal oscillator with the AT-cut crystal. Although we managed to obtain the frequency signal generated by the AT-cut crystal, the surface of the crystal is very sensitive such that waving your hands near the oscillator causes the waveform to change. To make the signal more stable, we construct another circuit design similar to the Colpitts oscillator.[5] One of the advantages of using this layout is that relatively low phase noise can be achieved, making them suitable for applications requiring stable and low-noise oscillation.		Then, we replace the 10Mhz crystal oscillator with the AT-cut crystal. Although we managed to obtain the frequency signal generated by the AT-cut crystal, the surface of the crystal is very sensitive such that waving your hands near the oscillator causes the waveform to change. To make the signal more stable, we construct another circuit design similar to the Colpitts oscillator.[5] One of the advantages of using this layout is that relatively low phase noise can be achieved, making them suitable for applications requiring stable and low-noise oscillation.
	< br clear=all>		<br clear=all>
	----		----
	==Second Set-Up==		==Second Set-Up==
			The circuit design and the actual circuit are shown in Figure (). 2N2222 bipolar junction transistors were used with a combination of capacitors and resistors. The purpose of the transistor is to amplify the voltage across the resonant circuit and stabilize the oscillations through a feedback loop. A DC power supply of 9V is applied across the circuit and an oscilloscope is connected to observe the waveform. Figure () shows the waveform, which seems to be a superposition of a square wave and another periodic signal which could be due to the aforementioned circuit impedance mismatches.
	[[File:Circuit diagram 2nd.png\|340px\|thumb\|right\|Circuit Diagram for 2nd setup]]		[[File:Circuit diagram 2nd.png\|340px\|thumb\|right\|Circuit Diagram for 2nd setup]]
	[[File:2nd setup.jpeg\|340px\|thumb\|~~right~~\|2nd Experimental setup]]		[[File:2nd setup.jpeg\|340px\|thumb\|left\|2nd Experimental setup]]
	The circuit design and the actual circuit are shown in Figure (). 2N2222 bipolar junction transistors were used with a combination of capacitors and resistors. The purpose of the transistor is to amplify the voltage across the resonant circuit and stabilize the oscillations through a feedback loop.		<br clear=all>
			We use the Anritsu MS2711D Spectrum Master to look for the resonance frequencies as a cross-reference to the frequency counter measurement. In Figure (), the resonance frequency of the piezoelectric quartz oscillator and its higher-order harmonics are shown. [insert resonance frequency narrow, wide scan of frequency] From the wide scan, we can see that the zeroth-order overtone occurs at approximately 6Mhz, and the higher-order harmonics occur in multiple integers of 6MHz.
	A DC power supply of 9V is applied across the circuit and an oscilloscope is connected to observe the waveform. Figure () shows the waveform, which seems to be a superposition of square wave and another periodic signal which could be due to the aforementioned circuit impedance mismatches.		[[File:Wide scan.jpeg\|340px\|thumb\|right\|Spectral survey scan using the Anritsu MS2711D Spectrum Master]]
			[[File:Narrow scan.jpeg\|340px\|thumb\|left\|Spectral narrow scan using the Anritsu MS2711D Spectrum Master]]
	We use the Anritsu MS2711D Spectrum Master to look for the resonance frequencies as a cross-reference to the frequency counter measurement. In Figure (), the resonance frequency of the piezoelectric quartz oscillator and its higher-order harmonics are shown. [insert resonance frequency narrow, wide scan of frequency] From the wide scan, we can see that the zeroth-order overtone occurs at ~~around~~ approximately 6Mhz, and the higher-order harmonics occur in multiple integers of 6MHz.
	[[File:Wide scan.jpeg\|340px\|thumb\|~~left~~\|Spectral survey scan using the Anritsu MS2711D Spectrum Master]]
	[[File:Narrow scan.jpeg\|340px\|thumb\|~~right~~\|Spectral narrow scan using the Anritsu MS2711D Spectrum Master]]
	<br clear=all>		<br clear=all>
	----		----

E0309214 at 04:05, 23 April 2024

2024-04-23T04:05:03Z

← Older revision		Revision as of 12:05, 23 April 2024
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	----		----
	==Working Principle==		==Working Principle==
	The working principle behind the QCM is based on the piezoelectric effect. The piezoelectric effect is the generation of electric charges by a crystalline material upon subjecting it to stress.[1] An oscillating electric field applied across the device induces an acoustic wave that propagates through the crystal and meets minimum impedance when the device's thickness is a half-integer multiple of the wavelength of the acoustic wave.[2] It is a shear mode device in which the acoustic wave propagates in a direction perpendicular to the crystal surface.[3] Therefore, crystals cut in specific crystal axes have to be used to utilize the shear mode.		[[File:AT and BT cut.png\|340px\|thumb\|right\|Orientation of AT- and BT- cut crystals]]The working principle behind the QCM is based on the piezoelectric effect. The piezoelectric effect is the generation of electric charges by a crystalline material upon subjecting it to stress.[1] An oscillating electric field applied across the device induces an acoustic wave that propagates through the crystal and meets minimum impedance when the device's thickness is a half-integer multiple of the wavelength of the acoustic wave.[2] It is a shear mode device in which the acoustic wave propagates in a direction perpendicular to the crystal surface.[3] Therefore, crystals cut in specific crystal axes have to be used to utilize the shear mode. A resonant oscillation in the crystal is achieved by putting the crystal in an oscillation circuit where the electrical and mechanical oscillations are close to the fundamental frequency of the crystal. Changes to the mass of the crystal would result in a proportional change in its natural frequency according to the Sauerbrey equation[4]

	A resonant oscillation in the crystal is achieved by putting the crystal in an oscillation circuit where the electrical and mechanical oscillations are close to the fundamental frequency of the crystal. Changes to the mass of the crystal would result in a proportional change in its natural frequency according to the Sauerbrey equation[4] <br />
	~~<br />~~
	<math>		<math>

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	<br />		<br />
	Another consideration would be the energy dissipation of the crystal to the surroundings. This is important, especially for viscoelastic films. Viscoelastic films violate the Sauerbrey condition that the bound mass is rigidly attached to the crystal without any slip. Such viscoelastic films dissipate energy via mechanical losses in the flexible mass.		Another consideration would be the energy dissipation of the crystal to the surroundings. This is important, especially for viscoelastic films. Viscoelastic films violate the Sauerbrey condition that the bound mass is rigidly attached to the crystal without any slip. Such viscoelastic films dissipate energy via mechanical losses in the flexible mass.
	~~[[File:AT and BT cut.png\|200px\|thumb\|left\|Orientation of AT- and BT- cut crystals]]~~		<br clear=all>
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	==Setup==		==Setup==
	The typical QCM set-up of piezoelectric quartz crystal microbalance is shown in Figure ().		The typical QCM set-up of piezoelectric quartz crystal microbalance is shown in Figure ().
	~~[[File:Typical setup.png\|center\|500px\|thumb\|Typical Setup for a QCM measurement]]~~		The oscillator circuit is connected to the power supply and sample stage mount where the piezoelectric quartz crystal is. We can determine the resonance frequency of the quartz crystal using an oscilloscope, frequency counter, or spectrum analyzer.
	~~<br />~~
	The oscillator circuit is connected to the power supply and sample stage mount where the piezoelectric quartz crystal is. We can determine the resonance frequency of the quartz crystal using an oscilloscope, frequency counter, or spectrum analyzer. To determine the feasibility of this QCM project, we built a simple oscillating circuit as a foundation to test if we can detect the resonance frequency of the quartz crystal. This also serves as a time buffer while waiting for the AT-cut quartz to be delivered. Figures () and () ~~shows~~ the electrical circuit diagram and its implementation on a breadboard. As the electrical current generated from the oscillation of the quartz crystal is an alternating current due to the piezoelectric effect, we employ the usage of logic gates called inverters to convert DC to AC for readout. Adding a resistor to the circuit allows for the control of the potential difference across the inverter. In this oscillating circuit, we use a 14-pin integrated circuit and measure the resonant frequency of a CMAC CK q5 crystal oscillator.		To determine the feasibility of this QCM project, we built a simple oscillating circuit as a foundation to test if we can detect the resonance frequency of the quartz crystal. This also serves as a time buffer while waiting for the AT-cut quartz to be delivered. Figures () and () show the electrical circuit diagram and its implementation on a breadboard.
	[[File:Circuit diagram 1st.png\|340px\|thumb\|left\|Circuit Diagram]][[File:1st setup.jpeg\|340px\|thumb\|right\|Experimental Setup]]
			As the electrical current generated from the oscillation of the quartz crystal is an alternating current due to the piezoelectric effect, we employ the usage of logic gates called inverters to convert DC to AC for readout. Adding a resistor to the circuit allows for the control of the potential difference across the inverter. In this oscillating circuit, we use a 14-pin integrated circuit and measure the resonant frequency of a CMAC CK q5 crystal oscillator.
			[[File:Circuit diagram 1st.png\|340px\|thumb\|left\|Circuit Diagram]]
			[[File:Typical setup.png\|340px\|thumb\|right\|Typical Setup for a QCM measurement]]
			[[File:1st setup.jpeg\|340px\|thumb\|right\|Experimental Setup]]
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	==Measurements==		==Measurements==
	A DC power supply of 5V is given and an oscilloscope is connected to see the signal's waveform. A frequency counter is connected to the electrical circuit and communicated to my computer via the Arduino Integrated Development Environment. The frequency is measured for 10 seconds 10 times to get an average. Eventually, a resonant frequency of 10.000001Mhz is recorded, which is very close to the 10Mhz value that was provided by the manufacturer. The waveform seen on the oscilloscope is observed to be periodic and looks like a square-wave oscillation. ~~[picture is waveform of first set up with 10Mhz]~~ There seem to be additional peaks periodically formed as well, which could likely come from circuit impedance mismatches. Mismatches in impedance between different components or sections of a circuit can cause signal reflections and distortions, leading to additional peaks in the waveform. We would have to adjust the values of the capacitors and resistors.		[[File:1st setup waveform.jpeg\|340px\|thumb\|right\|Waveform observed with an oscilloscope using the CMAC CK q5 crystal oscillator]]
	~~< br/>~~		[[File:10mhz waveform.jpeg\|340px\|thumb\|right\|Waveform observed with an oscilloscope using the AT-cut quartz crystal]]
	Then, we replace the 10Mhz crystal oscillator with the AT-cut crystal. ~~[picture is waveform of first set up]~~ Although we managed to obtain the frequency signal generated by the AT-cut crystal, the surface of the crystal is very sensitive such that waving your hands near the oscillator causes the waveform to change. To make the signal more stable, we construct another circuit design similar to the Colpitts oscillator.[5] One of the advantages of using this layout is that relatively low phase noise can be achieved, making them suitable for applications requiring stable and low-noise oscillation.		A DC power supply of 5V is given and an oscilloscope is connected to see the signal's waveform. A frequency counter is connected to the electrical circuit and communicated to my computer via the Arduino Integrated Development Environment. The frequency is measured for 10 seconds 10 times to get an average. Eventually, a resonant frequency of 10.000001Mhz is recorded, which is very close to the 10Mhz value that was provided by the manufacturer.

			The waveform seen on the oscilloscope is observed to be periodic and looks like a square-wave oscillation. There seem to be additional peaks periodically formed as well, which could likely come from circuit impedance mismatches. Mismatches in impedance between different components or sections of a circuit can cause signal reflections and distortions, leading to additional peaks in the waveform. We would have to adjust the values of the capacitors and resistors.

			Then, we replace the 10Mhz crystal oscillator with the AT-cut crystal. Although we managed to obtain the frequency signal generated by the AT-cut crystal, the surface of the crystal is very sensitive such that waving your hands near the oscillator causes the waveform to change. To make the signal more stable, we construct another circuit design similar to the Colpitts oscillator.[5] One of the advantages of using this layout is that relatively low phase noise can be achieved, making them suitable for applications requiring stable and low-noise oscillation.
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	==Second Set-Up==		==Second Set-Up==
	The circuit design and the actual circuit is shown in Figure (). 2N2222 bipolar junction transistors were used with a combination of capacitors and resistors. The purpose of the transistor is to amplify the voltage across the resonant circuit and ~~stabilise~~ the oscillations through a feedback loop. ~~<br />~~		[[File:Circuit diagram 2nd.png\|340px\|thumb\|right\|Circuit Diagram for 2nd setup]]
	A DC power supply of 9V is applied across the circuit and an oscilloscope is connected to observe the waveform. Figure () shows the waveform, which seems to be a superposition of square wave and another periodic signal which could be due to the aforementioned circuit impedance mismatches. ~~[insert second set up]~~ We use the Anritsu MS2711D Spectrum Master to look for the resonance frequencies as a cross-reference to the frequency counter measurement. In Figure (), the resonance frequency of the piezoelectric quartz oscillator and its higher-order harmonics are shown. [insert resonance frequency narrow, wide scan of frequency] From the wide scan, we can see that the zeroth-order overtone occurs at around approximately 6Mhz, and the higher-order harmonics occur in multiple integers of 6MHz.		[[File:2nd setup.jpeg\|340px\|thumb\|right\|2nd Experimental setup]]
			The circuit design and the actual circuit are shown in Figure (). 2N2222 bipolar junction transistors were used with a combination of capacitors and resistors. The purpose of the transistor is to amplify the voltage across the resonant circuit and stabilize the oscillations through a feedback loop.

			A DC power supply of 9V is applied across the circuit and an oscilloscope is connected to observe the waveform. Figure () shows the waveform, which seems to be a superposition of square wave and another periodic signal which could be due to the aforementioned circuit impedance mismatches.

			We use the Anritsu MS2711D Spectrum Master to look for the resonance frequencies as a cross-reference to the frequency counter measurement. In Figure (), the resonance frequency of the piezoelectric quartz oscillator and its higher-order harmonics are shown. [insert resonance frequency narrow, wide scan of frequency] From the wide scan, we can see that the zeroth-order overtone occurs at around approximately 6Mhz, and the higher-order harmonics occur in multiple integers of 6MHz.
			[[File:Wide scan.jpeg\|340px\|thumb\|left\|Spectral survey scan using the Anritsu MS2711D Spectrum Master]]
			[[File:Narrow scan.jpeg\|340px\|thumb\|right\|Spectral narrow scan using the Anritsu MS2711D Spectrum Master]]
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	==Second Measurement==		==Second Measurement==

← Older revision		Revision as of 12:37, 23 April 2024
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	==Second Measurement==		==Second Measurement==
	The procedure for the frequency counter measurements is the same as that of the 10MHz crystal oscillator. The fundamental resonant frequency is measured to be 5.986804MHz. Using this as the reference resonance frequency, we can now test its effectiveness in mass measurements with the Sauerbrey equation.		The procedure for the frequency counter measurements is the same as that of the 10MHz crystal oscillator. The fundamental resonant frequency is measured to be 5.986804MHz. Using this as the reference resonance frequency, we can now test its effectiveness in mass measurements with the Sauerbrey equation.
	[[File:Permanent marker.jpeg\|340px\|thumb\|left\|Depiction of how ink was placed on the quartz crystal plate]]		[[File:Permanent marker.jpeg\|340px\|thumb\|left\|Figure 11: Depiction of how ink was placed on the quartz crystal plate]]
	[[File:Ink no signal.jpeg\|340px\|thumb\|right\|No spectral signatures from measurement]]		[[File:Ink no signal.jpeg\|340px\|thumb\|right\|Figure 12: No spectral signatures from measurement]]
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	[[File:Increase power.jpeg\|340px\|thumb\|right\|Increasing DC power supply shows a fundamental mode of resonance]]		[[File:Increase power.jpeg\|340px\|thumb\|right\|Figure 13: Increasing DC power supply shows a fundamental mode of resonance]]
	Firstly, a permanent marker is used where we dot the center of the quartz crystal shown in Figure (). [insert permanent marker ink] Initially, there was no signal shown in Figure (). ~~[Explain why]~~ However, increasing the DC supply voltage sufficiently allows the fundamental mode to be observed as shown in Figure (). We repeated the frequency counter measurements and found the new resonance frequency to be 5.984613MHz.		Firstly, a permanent marker is used where we dot the center of the quartz crystal shown in Figure 11. [insert permanent marker ink] Initially, there was no signal shown in Figure 12. This is most likely due to the damping of the resonance oscillations due to the added mass, thereby decreasing the voltage gain. However, increasing the DC supply voltage sufficiently allows the fundamental mode to be observed as shown in Figure 13. We repeated the frequency counter measurements and found the new resonance frequency to be 5.984613MHz.

	To test the mass limit of this setup, a small Blu Tack weighing 2.1 grams is placed on the center of the oscillator. A new oscillator is used so that the dried ink does not interfere with the measurement. The Spectrum Master did not record any spectral features, which suggests that the oscillation of the crystal is too damped to be detected and that the gain is insufficient. Increasing the DC power supply to 18V is inadequate to produce a spectral feature. For safety purposes, this will be the limit that we shall test.		To test the mass limit of this setup, a small Blu Tack weighing 2.1 grams is placed on the center of the oscillator. A new oscillator is used so that the dried ink does not interfere with the measurement. The Spectrum Master did not record any spectral features, which suggests that the oscillation of the crystal is too damped to be detected and that the gain is insufficient. Increasing the DC power supply to 18V is inadequate to produce a spectral feature. For safety purposes, this will be the limit that we shall test.
	[[File:Blu tack.jpeg\|340px\|thumb\|left\|Depiction of how Blu tack was placed on the quartz crystal plate]]		[[File:Blu tack.jpeg\|340px\|thumb\|left\|Figure 14: Depiction of how Blu tack was placed on the quartz crystal plate]]
	[[File:Blu tack no signal.jpeg\|340px\|thumb\|right\|No spectral signatures from measurement]]		[[File:Blu tack no signal.jpeg\|340px\|thumb\|right\|Figure 15: No spectral signatures from measurement]]
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	Based on the Sauerbrey equation, the decrease in resonance frequency of 2191Hz corresponds to an increase in mass of 969 micrograms. This value is derived by using the following:		Based on the Sauerbrey equation, the decrease in resonance frequency of 2191Hz corresponds to an increase in mass of 969 micrograms. This value is derived by using the following:
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	*The mass is evenly distributed over the active area of the crystal.		*The mass is evenly distributed over the active area of the crystal.

	Based on these conditions, the second and third conditions are not fulfilled.		Based on these conditions, the second and third conditions are not fulfilled. In the next section, we discuss what are how these assumptions can be relaxed.
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