MicroVacuum QCM-I Mini User manual

Volume 1. QCM-I Mini and eQCM-I Mini User Manual Rev3
QCM-I Mini and eQCM-I Mini Operator’s Manual Edition: 2018/12
© MicroVacuum Revision: 3
1
QCM-I Mini and eQCM-I Mini
QUARTZ CRYSTAL MICROBALANCE WITH
IMPEDANCE ANALYSIS
User Manual
 1993-2018 MicroVacuum Ltd.
Kerékgyártó u. 10, Budapest, H-1147, Hungary
Phone [phone] • Fax [phone]
E-mail: [e-mail]
Web: http://www.microvacuum.com/
Volume

2
QCM-I Mini and eQCM-I Mini User Manual Edition: 2018/12
© MicroVacuum Revision: 3
TABLE OF CONTENT S
SAFETY ............................................................................................................................................................... 5
1.
General Safety .............................................................................................................................................................................. 5
Measuring Head, Sensor Holder and Flow Cell ............................................................................................................................. 6
INTRODUCTION .................................................................................................................................................. 7
2.
QCM-I MINI PRINCIPLE OF OPERATION .............................................................................................................. 8
3.
3.1 QCM-I MEASUREMENT PRINCIPLE ............................................................................................................................... 8
3.2 LIMITS OF OPERATION ................................................................................................................................................ 9
Assumptions ................................................................................................................................................................................. 9
Maximum Loads ......................................................................................................................................................................... 10
3.3 LOCATING RESONANT FREQUENCIES ............................................................................................................................ 10
3.4 RESONANCE CURVE ANALYSIS .................................................................................................................................... 10
Resonance Modeling (Lorentz curve) ......................................................................................................................................... 10
3.5 QCM-I MINI INSTRUMENT DESCRIPTION ..................................................................................................................... 12
General ....................................................................................................................................................................................... 12
Temperature Measurement and Temperature Control Module ................................................................................................ 13
Power Supplies (External) ........................................................................................................................................................... 13
PC for Running BioSense Software ............................................................................................................................................. 13
BioSense Software ...................................................................................................................................................................... 13
Measurement Channels .............................................................................................................................................................. 13
Built-in Thermal Chamber and Sensor Holder with Flow-Cell ..................................................................................................... 13
External Sensor Holder ............................................................................................................................................................... 13
3.6 ELECTROCHEMICAL QCM-I........................................................................................................................................ 13
Potentiostat ................................................................................................................................................................................ 14
3.7
QCM-I M
INI
S
PECIFICATION
.................................................................................................................................... 15
GETTING THE EQUIPMENT READY FOR USE ...................................................................................................... 16
4.
4.1 UNPACKING QCM-I MINI ......................................................................................................................................... 16
4.2 UNPACKING THE COMPUTER ...................................................................................................................................... 16
4.3 QCM-I MINI INSTALLATION WITH MICROSOFT SURFACE PRO .......................................................................................... 17
USB Hub Accessory ..................................................................................................................................................................... 17
4.4 INSTALLATION USING DESKTOP PC OR NUC COMPUTER .................................................................................................. 19
4.5 INSTRUMENT TESTING .............................................................................................................................................. 21
4.6 EQCM-I INSTALLATION ............................................................................................................................................. 21
4.7 EQCM-I ELECTRODE CONNECTIONS ............................................................................................................................ 21
TEMPERATURE CONTROL ................................................................................................................................. 23
5.
SENSORS .......................................................................................................................................................... 24
6.
6.1 SENSORS ................................................................................................................................................................ 24
Geometry .................................................................................................................................................................................... 24
Electrode Materials..................................................................................................................................................................... 25
Electrode Coatings ...................................................................................................................................................................... 25

3
QCM-I Mini and eQCM-I Mini User Manual Edition: 2018/12
© MicroVacuum Revision: 3
6.2 SENSOR LIFE AND PERFORMANCE................................................................................................................................ 25
Useful Life ................................................................................................................................................................................... 25
Temperature Effects ................................................................................................................................................................... 26
6.3 SENSOR HANDLING .................................................................................................................................................. 26
6.4 SENSOR CLEANING ................................................................................................................................................... 27
UV-Ozone Cleaning ..................................................................................................................................................................... 28
Basic Piranha ............................................................................................................................................................................... 28
Acid Piranha ................................................................................................................................................................................ 28
Detergent .................................................................................................................................................................................... 29
Other Cleaning Methods............................................................................................................................................................. 29
FLOW CELL ASSEMBLY ...................................................................................................................................... 30
7.
7.1 STANDARD FLOW CELL ASSEMBLY ............................................................................................................................... 30
7.2 ELECTROCHEMICAL FLOW CELL ASSEMBLY .................................................................................................................... 32
FLOW-CELL FLUIDIC CONFIGURATIONS ............................................................................................................ 33
8.
8.1 PREPARING SOLUTIONS ............................................................................................................................................. 33
8.2 MANUAL STATIC CELL ............................................................................................................................................... 33
8.3 PERISTALTIC PUMP ................................................................................................................................................... 34
8.4 PERISTALTIC PUMP AND SELECTOR VALVE ..................................................................................................................... 35
8.5 PERISTALTIC PUMP AND SAMPLE INJECTION VALVE ........................................................................................................ 35
SENSOR HOLDERS, ADAPTORS AND MODULES ................................................................................................ 37
9.
Standard Flow Cell ...................................................................................................................................................................... 37
Dummy Sensor Module .............................................................................................................................................................. 37
Immersion and Open Sensor Holder ........................................................................................................................................... 38
Electrochemical Flow Cell ........................................................................................................................................................... 38
Ag/AgCl Reference Electrode ...................................................................................................................................................... 38
High Pressure Sensor Holder ...................................................................................................................................................... 39
Vacuum Sensor Holder ............................................................................................................................................................... 40
Microscopy ................................................................................................................................................................................. 40
Low Profile Holder ...................................................................................................................................................................... 41
Channel A: External Sensor-Holder Adaptor ............................................................................................................................... 41
Calibration Kit ............................................................................................................................................................................. 42
Custom External Sensor-Holder .................................................................................................................................................. 42
BIOSENSE 3 SOFTWARE FOR QCM-I MINI ......................................................................................................... 43
10.
10.1 USER LOGIN ....................................................................................................................................................... 43
Evaluation Mode ......................................................................................................................................................................... 43
TROUBLESHOOTING ......................................................................................................................................... 43
11.
11.1 ERROR MESSAGES ............................................................................................................................................... 43
SUPPORT .......................................................................................................................................................... 44
12.
12.1 HOW TO ESTABLISH REMOTE CONTACT? ................................................................................................................. 44
WARRANTY ...................................................................................................................................................... 45
13.
APPENDIX 1: SENSOR DATA SHEETS ................................................................................................................. 46
14.
APPENDIX 2: SENSOR-HOLDER MODULE DATA SHEETS .................................................................................... 47
15.

4
QCM-I Mini and eQCM-I Mini User Manual Edition: 2018/12
© MicroVacuum Revision: 3
Windows® and Excel® are registered trademarks of the Microsoft Corporation

Safety 5
QCM-I Mini and eQCM-I Mini User Manual Edition: 2018/12
© MicroVacuum Revision: 3
Safety
1.
In no event shall MicroVacuum ever be held responsible or liable for any direct, indirect, incidental,
special or consequential damages or costs whatsoever resulting from or related to the use or misuse of
the QCM-I Mini instrument or components thereof, even if MicroVacuum has been advised, knows of,
or should be aware of the possibility of such damages. MicroVacuum emphasizes the importance of
consulting experienced and qualified professionals to assure the best results when using the QCM-I
Mini.
General Safety
WARNING!
The safety requirements listed in this manual must be followed in order to avoid personal injury and
damage to the QCM-I Mini instruments.
WARNING!
RISK OF ELECTRICAL SHOCK. Do not connect this instrument to electrical power if the enclosure is
damaged or any of the covers or panels is removed. Make sure the voltage rating on the
instrumentation matches the line voltage available in the lab. Connect only to outlets with safety earth
ground. Make sure that the power cord is easily accessible when the equipment has been installed.
WARNING!
RISK OF ELECTRICAL SHOCK OR FIRE HAZARD. Switches may produce electrical sparks. Do not
use the QCM-I Mini instruments in the presence of flammable gases, fumes or liquids.
The instrument has been designed for indoor use only. Do not expose it to rain, snow or dust. During
storage or transport the instrument should be kept dry. Temperatures below 0ºC and above 65ºC
should be avoided. Do not operate at ambient temperatures below 5ºC and above 30ºC.
CAUTION!
Use only as specified in the operating instructions. Follow all instructions. Skipping steps can result in
damage to the QCM-I Mini instrument.
Handle carefully when removing the instrument from the transport packaging. The product must always
be shipped in either the original packaging supplied with the QCM-I Mini, or equivalent.
CAUTION!
Do not use force when connecting or disconnecting connectors as damage may occur.
Do not subject the equipment to external shocks.
Do not block or restrict ventilation slots.
Do not expose any parts other than the sample volume in the flow module(s) to water or other liquids.
CAUTION!
If liquid is spilled on the instrument, disconnect it from the power source and have it checked by an
authorized person.
Refer to the safety information from the supplier and general safety regulations in your country when
you work with chemicals.
Carry out appropriate decontamination if equipment is exposed to hazardous material.
Do not install substitute parts or perform any unauthorized modification to the product.
Return the product to MicroVacuum or other qualified and authorized personnel for service and repair to
ensure that safety features are maintained. Before returning the instrument it must be free of hazardous
contamination.
For safety instructions and operation of peripheral equipment, e.g. the personal computer, read the
safety instructions and the manual provided by the manufacturer carefully.

Safety 6
QCM-I Mini and eQCM-I Mini User Manual Edition: 2018/12
© MicroVacuum Revision: 3
Turn the QCM-I Mini or eQCM-I Mini off when not in use. An appropriate risk assessment should be
undertaken before the instrument is left operating unattended.
Measuring Head, Sensor Holder and Flow Cell
WARNING!
RISK OF FIRE HAZARD. Use only sample liquids with a self-ignition point higher than 85°C in the
sample volume of the flow modules.
Parts of the sensor holder and flow cells can become hot.
Do not expose any parts other than the sample volume to water and other liquids.
If liquid is spilled inside the electronics part of the sensor holder, disconnect it from the electronics unit
and have it checked by an authorized person.

Introduction 7
QCM-I Mini and eQCM-I Mini User Manual Edition: 2018/12
© MicroVacuum Revision: 3
Introduction
2.
The QCM-I Mini is a precision instrument for the determination of the mass and viscoelastic properties
of thin films attached to the surface of a quartz crystal sensor. These films, which may be a wide range
of molecular or atomic layers from metals to physisorbed polymers, surfactants or immobilized
biological samples, are monitored in real time either in liquid or in the vapor phase. The measurement
is made by monitoring the change in resonant frequency spectrum of the oscillating piezoelectric sensor
crystal. In water the acoustic transverse wave created extends into the solution above the sensor
surface, decaying rapidly with a penetration depth of ~250 nm for a 5 MHz crystal. The technique can
measure changes in the layers over a nm to micron thickness range or ng/cm2 to g/cm2 mass range,
as well as changes in the solution viscosity. In solution, the mass determined is the “wet mass” or
hydrated mass which corresponds to the solid material that makes up the film as well as solvent and
ions etc. that are contained within the film and closely coupled to the oscillation of the film.
This manual describes the principles of operation and how to set up the instrument together with safety
and technical information for the correct operation and maintenance of the QCM-I Mini. It is important
that the user familiarize themselves with these requirements if the equipment is to be operated correctly
and to its best. Please read all sections before using the equipment.
As with all precision instruments, it is not recommended that the user undertake maintenance or
calibration unless specifically trained to do so by the manufacturer. If for whatever reason the
instrument ceases to operate correctly, the user should contact the vendor for guidance on whether the
instrument needs to be serviced by a qualified service engineer or returned to the vendor for repair.
Under no circumstances should the instrument be dismantled or operated without the fitted cover and
attention should be taken at all times to the warnings detailed in the operator’s manual.
This User Manual (Volume 1) which focuses on the hardware aspects of the instrument should be read
in conjunction with the Software Manual (Volume 2) also provided with the equipment.

QCM-I Mini Principle of Operation 8
QCM-I Mini and eQCM-I Mini User Manual Edition: 2018/12
© MicroVacuum Revision: 3
QCM-I Mini Principle of Operation
3.
3.1 QCM-I MEASUREMENT PRINCIPLE
The Quartz Crystal Microbalance (QCM) technique monitors the resonant frequency of a piezoelectric
quartz crystal sensor in response to an alternating voltage applied between electrodes on its two faces.
The crystals are cut so that they oscillate in a thickness shear mode, with opposing faces travelling in
opposite directions as shown in Figure 1. AT-cut quartz crystals are most commonly used as QCM
sensors because of their superior mechanical and piezoelectric properties, and because they can be
cut to give nearly zero temperature coefficients at room temperature. The resonant frequency
corresponds to the excitation of the acoustic standing wave across the thickness of the quartz and top
and bottom electrodes. If a thin rigid layer is added to the surface of one of the electrodes, the acoustic
wave extends through this layer and the resonant frequency drops. The reduction in the frequency can
be related to the change in areal mass (m/A) on the surface of one side of the crystal by the
Sauerbrey equation1:
fn = -2n.f12.(m/A)/(qq)½ (Hz) (1)
m/Afn .(qq)½ / (-2n.f12) (ng/cm2) (2)
Where fn is the change in resonant frequency of the nth overtone of a crystal of fundamental frequency
f1, m is the change in mass (g), A is the area (cm2), q is the density of quartz (2.648 g/cm3) and q is
the Shear Modulus of quartz (2.947x1011 gcm-1s-2).
For a crystal with fundamental frequency of 5 MHz, its mass sensitivity [m/(f.A)] is -17.7 ngcm-2/Hz.
The areal mass data from the Sauerbrey equation can also be expressed as a (Sauerbrey) thickness
(ds) by using an estimated density for the layer , which is often taken as 1 gcm-3.
ds = (m/A) / (.100) (nm) (3)
The crystal can also oscillate at overtone frequencies, which correspond to the odd harmonics; 3x, 5x,
7x etc. and measurements can also be made at these frequencies.
Figure 1: Schematic diagram of a QCM measurement, showing the shear displacement of the quartz at
fundamental and 3rd harmonic frequencies. The plot shows a conductance-frequency response obtained from an
impedance measurement with a network analyzer; resonant frequency and band width are marked.
In the QCM-I technique the resonant frequency is obtained using a network analyzer, which measures
the impedance spectrum of the crystal as a function of frequency. The resonant peak obtained at the
fundamental frequency is also shown in Figure 1. In addition to the frequency of the resonant
maximum, the Full Width at Half Maximum (FWHM) is also obtained. The FWHM can be related to the
dissipation (D, determined by QCM-D using the “ring-down” technique) and is inversely proportional to
the Quality factor (Q) of the crystal:
1 Sauerbrey, G. Z. Phys. 1955, 155, 206.

QCM-I Mini Principle of Operation 9
QCM-I Mini and eQCM-I Mini User Manual Edition: 2018/12
© MicroVacuum Revision: 3
FWHM / f = D = 1/Q (4)
The FWHM/f measured from the impedance and D measured by the ring-down technique (QCM-D)
have been shown to be the same parameter, just measured in two different ways2.
When a rigid film is deposited on the sensor surface, the FWHM does not change and f/n is the same
for the fundamental frequency and the overtones. However, if a bare crystal is immersed in a viscous
liquid, or if a viscoelastic film is deposited on the sensor surface from solution, then as well as a
reduction in the frequency, the FWHM will increase; this is shown in Figure 2. For a viscoelastic layer
the frequency change, fn/n, is also smaller for higher overtones.
The QCM-I signal Frequency and FWHM response to the viscosity and density of Newtonian solution
(s) is given by3:
fn = -n1/2 f13/2 (ss )1/2 / (qq)1/2 (Hz) (5)
FWHM = 2 n1/2f13/2 (ss )1/2 / (qq)1/2 (Hz) (6)
This means that the response measured for a bulk solution change, due to different viscosity or density
of the new solution follows the relationship: FWHMn/fn= 2.
Figure 2: Change in resonance of a bare QCM sensor (blue) on immersion in a liquid (red).
3.2 LIMITS OF OPERATION
Assumptions
Measurements can be made for the deposition of a very wide range of layers, however analysis of film
properties generally makes the following assumptions:
 Uniform film distribution – the surface is completely covered with a uniform film
 Good adhesion of the film to the surface
 Thin film approximation – the film thickness is significantly less than the thickness of the crystal
 Rigid layer – Sauerbrey analysis to directly determine the mass from the frequency change
requires this, otherwise visco-eleastic models are required to stop underestimation of the mass
change. The extent of the error is dependent on the film thickness as well as the solution
viscosity, if the measurement is in solution.
2 D. Johannsmann, Viscoelastic, mechanical and dielectric measurements on complex samples with the
quartz crystal microbalance. Phys. Chem. Chem. Phys. 10, 4516–4534 (2008)
3 K. Kanazawa, J. G. Gordon, Anal. Chim. Acta 1985, 175, 99–105.

QCM-I Mini Principle of Operation 10
QCM-I Mini and eQCM-I Mini User Manual Edition: 2018/12
© MicroVacuum Revision: 3
For data analysis and more complex modelling of QCM experiments where overtone data is available,
the fundamental frequency is often not used because it does not always fit consistently with the
overtone data. For some instruments it may also not be commonly measured due to issues with signal
stability. The reason for this is likely to be due to the magnitude of displacement at the crystal surface,
which is approximately inversely proportional to square of the overtone number. Ie. the surface
displacement U0 at the fundamental frequency is 9x that of the 3rd harmonic at the same Q.
U0 = 4UelQq/(n)2 (7)
Where Uel is the electrical driving amplitude, Q the crystal quality factor, q is the piezoelectric strain
coefficient (3.1 x 10-12 m/V for AT cut quartz) and n is the overtone number.
This is likely to make it more sensitive to edge effects or stresses within the crystal. However for non-
rigid layers, the lower the harmonic, the closer the calculated Sauerbrey mass will be to the actual
hydrated mass. Indeed for some systems, such as coupled nanoparticles or vesicles, the reduction of
the frequency response for the overtones can be so large that the fundamental and overtones give
apparent mass changes in opposite directions and potentially wholly incorrect interpretation of the data
if only the overtone data is collected. For this reason it is recommended that the fundamental frequency
data is always collected.
Maximum Loads
QCM sensor crystals can be coated with virtually any material as long as it can be deposited in a
sufficiently thin, uniform and well-attached layer. Layer thicknesses typically vary from a few Angstrom
to a few micrometers. The maximum layer thickness depends on the viscoelastic properties of the
coating material. As a general rule, thicker layers are possible for more rigid coating materials.
The maximum load on a crystal is limited by two factors: (1) total damping or (2) lost sensitivity. For
highly viscous or solid materials, the damping of the crystal increases with increasing layer thickness.
At a certain thickness (usually a couple of micrometers) the damping becomes so high that the crystal
can no longer be driven, i.e. the measurement fails due to lack of oscillation. More elastic materials do
not couple completely to the crystal’s oscillation. With increasing layer thickness the outermost parts of
the attached layer will couple weakly and at a certain thickness (usually a few micrometers) it is lost
completely. Oscillation is still detected, and a frequency is still measured, but the equipment can only
sense the part of the layer in the vicinity of the crystal-layer interface.
3.3 LOCATING RESONANT FREQUENCIES
In order to determine the resonant frequencies to track for a measurement, during the measurement
initialization, the network analyzer scans through a wider frequency range measuring the sensor crystal
admittance (1/impedance) based on the nominal crystal frequency. Once it has identified conductance
maxima within this region it selects a narrower region to make measurements at smaller frequency
intervals for a better defined resonance curve. The user can do a similar scan using the network
analyser (Frequency Scan) between any frequencies from 0.05 to 80 MHz.
3.4 RESONANCE CURVE ANALYSIS
Resonance Modeling (Lorentz curve)
For each of the selected sensor resonances, the conductance (G) and susceptance (B) values as a
function of frequency (the real and imaginary components of the admittance) are fitted to a Lorentzian
model for the Crystal oscillator. The fit parameters are Gmax, FWHM, Frequency, Goff, Boff, Fi and
residual, derived from the equivalent circuit4, shown in Figure 3. The resonant frequency and FWHM
4 D. Johannsmann, The Quartz Crystal Microbalance in Soft Matter Research: Fundamentals and Modeling,
Springer International Publishing, Switzerland, 2015.