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Langmuir-Blodgett Instruments Tensiometers Goniometers Surface Chemistry |
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KSV 2000 LB-system KSV 2000 System is a modular Langmuir trough system which expands from a conventional film balance to a high performance Langmuir-Blodgett instrument or to a fully equipped alternating multilayer Langmuir-Blodgett system. The heart of the system is the mainframe module and the system set-up is built around it by using the modules and accessories. All the modules are easily plugged into the mainframe and the system set-up is factory installed and ready to use. The configuration can be up-graded later with various accessories and modules. KSV 2000 System is available in three basic modular set-ups.
System 1 Langmuir Film Balance for conventional
Langmuir film studies System 2 Langmuir-Blodgett instrument for
deposition of Langmuir-Blodgett films System 3 Alternating multilayer Langmuir-Blodgett trough for fabrication of films consisting of two molecular materials Specifications KSV 2000 System 1 Langmuir film balance for conventional monolayer analyses and Langmuir-Film
experiments. Biomembrane and enzyme kinetic reaction studies. Upgradable to
System 2 and 3. Module configuration:
KSV 2000 System 2 Langmuir-Blodgett instrument for unsupervised deposition of ordered
multilayer LB-films and for KSV 5000 System 1 applications. Upgradable to System
3. Module configuration:
KSV 2000 System 3 Alternate Multilayer Layer Langmuir-Blodgett system for unsupervised
deposition of ordered layers of two different monolayer molecules and System 1
and System 2 applications. Module configuration:
Catalogue summary Symmetric compression KSV uses symmetric compression of the monolayer in all of its troughs. Symmetric compression, achieved by enclosing the monolayer in between two moving barriers, produces uniform shear through out the whole film area minimising possible parabolic film flow effects. The accuracy and reproducibility of the film pressure measurement with the Wilhelmy Plate is increased because the plate is evenly compressed from both sides. No floating of the plate with the flow will occur, even with stiffest of films. With simple arrangement the barriers can be modified to move in the same
direction, for example to go over various subphases in biological applications. Film deposition The key issue in successful film deposition is to maintain monolayer molecular orientation unchanged during the transfer from air/water interface onto a solid substrates. The parabolic film flow effect, centre moving faster than sides, caused by the friction between the side walls and the film is the major source for orientation changes during the deposition. This problem comes evident especially with conventional single barrier and band type of systems where monolayer flows to one direction only. These systems further produces another problem in connection of substrate deposition. Since the face of the substrate will be against the film flow there will be significant back drag on the opposite side of the substrate causing localised orientation changes. Consequently the pressure measurement, when performed near the deposition or at back of substrate will become unreliable because of the local instabilities. The symmetric compression avoids the back drag phenomena and pressure measurement problems during the deposition process. The film deposition is performed right at the film compression centre where the film reaches its highest degree of orientation. Orientation changes during deposition will not occur since film compression is uniform. The dipper is equipped with high precision DC motor to ensure smoothest
possible movement of the dipper shaft. The speed of the shaft, the number of
deposition cycles, dwell times, partial depositions etc. all are user
programmable and operation controlled by the software. The substrates can be
dipped perpendicular or parallel to the barrier movement. Depositing alternating multilayer films The unique substrate transport system of the KSV 2000 System 3 with a clean subphase in the middle of the two trough compartments makes it possible to deposit the alternating LB-layers in any desired stacking order. The Film Deposition System, the dipper, is capable of depositing alternating LB-films of x, z, y or any other type fully automatically, continuously and without cross contamination. Stacking order of the layers is dependent only on the chemistry of the molecules not on the instrument hardware. The dipper consist of two independent arms equipped with automatic clamps to hold the substrate. Rotation of the dipper, vertical movement of its arms and opening and closing of the clamps is all software controlled. The upper arm is for airborne travel and the lower arm for under subphase travel of the substrate. There is no cross contamination as only the substrate penetrates the film and not the mechanics moving it. The trough, made of form sintered solid PTFE, consist of two rectangular shape compartments each having its own symmetric compression system and film balance. Both compartments function independent from the other. Film compression, pressure monitoring and deposition processes for each
compartment is controlled by a KSV Multitasking software. Software KSV 2000 is run by a multitasking software allowing creation of complex measurement sequences without software modifications. Software includes ready written and menu driven programs covering most of known LB-film experiments. No reprogramming is needed and the user is directed trough the set up programs step by step. Standard programs include:
Trough geometry The wide variety of LB-film applications requires flexibility in the
geometrical design of the trough. Very often special shapes and sizes are
needed. The use original rectangular Langmuir trough with moving barriers offers
greatest flexibility in geometrical design of the troughs. In band and moving
wall types of systems the band defines the trough shape while acting as a
barrier. In such a systems the trough geometry is fixed and can't be changed. Customised and standard troughs The size of the bottom PTFE block of the KSV's troughs is standardised making
it possible to manufacture nearly shape or size troughs. No matter whether deep
or shallow, long and narrow or short and wide all shapes can be easily made and
without any extra cost. Cleaning and dismantling Easy access to troughs and barriers, their quick dismantling and cleaning
plays vital role in every day use of LB-trough. KSV's troughs are independent
modules from the main instrument body and can they be dismantled simply by
lifting by hand. The instrument body has a special guide rail for snap-in
mounting of the trough. The barriers are conveniently and accurately placed to
their original positions in their riders. All sharp angles are rounded for
thorough cleaning. Subphase temperature control The temperature regulation and maintenance of accurate constant subphase temperature is of one of the fundamental preconditions for successful film fabrication. The smaller is the subphase volume the more accurate and fast is its temperature regulation. The KSV PTFE trough with bottom thickness of approx. 1,0 mm is cemented on an aluminium heat plate. Aluminium, being a good conductor, distributes energy evenly throughout the whole bottom area while responding fast and accurately to the temperature changes. The walls of the dipping well are also thermostated to minimise the temperature difference in between the well and the rest of the trough bottom area. Subphase water temperature is regulated by running thermostated water from an
external circulator through the heat plate. The temperature sensor probe,
situated in the subphase, constantly monitors subphase temperature while
commanding the external circulator. Trough material A pure solid PTFE (polytetrafluoroethylene) is used in all KSV's troughs mainly because it is inert and highly hydrophobic and easy to clean. All troughs are made of solid block of from sintered PTFE. Sprayed PTFE coating is not used due to its porousness, impurities caused by
spraying process and because it can't be repaired in case of scratches. Leak proof barriers Often it is thought that in order to make good seal in between the PTFE trough and barriers it is necessary to overfill the trough. Doing so usually caused overspilling of subphase or film leakage over the trough edges. KSV avoids these problems by a hydrophilic barrier material. Advantage are quite obvious especially when experimenting high surface pressures. To prevent film leakage over the edges surface level of the subphase should
be kept as low as possible. With low surface pressures this causes no problems
either with hydrophilic or hydrophobic surface barriers. Special troughs Enzyme kinetics trough A zero-order trough was originally developed by Prof. Verger de Haas for studying enzyme reactions in monomolecular films. It offers the advantage of linear (zero-order) enzyme kinetics, and possibility of using mixed lipid monolayers of constant composition as substrates for lipolytic enzymes. The zero-order trough consists of a reaction compartment and a reservoir compartment separated with a glass bridge just underneath the water surface. The bridge prevents mixing of the subphases of the two compartments. The enzymes or molecules are injected into the subphase of the reaction compartment. The adsorbed molecules increase the surface pressure of the monolayer and if
the pressure is being kept constant by moving the barrier the rate of the
adsorption and the number of molecules adsorbed can be calculated. Conductivity trough The conductivity trough facilitates the measurement of the lateral
conductivities of monolayer films on water. Due to the glass bridge the
electrical resistance between the electrodes is increased to the extent where
one can easily measure films with conductivity better than one S/cm.
Conductivity measurements are performed under CO2 free atmosphere and highly
purified water is used. Microscopy trough Using mixed monolayers with fluorescent dyes one can observe the possible phase separation of the different substances through the quartz window on the bottom of the trough. The trough is standard KSV trough with out dipping well. Quartz optical window is fixed into the bottom of the trough. Optics of the microscope are arranged below the trough and the monolayer is observed vertically beneath the trough. Surface potential measurement trough The surface potential of floating monolayer can be measured with KSV 5000SP
module and KSV surface potential measurement trough. The trough is designed long
and narrow in order to have maximum compression area. It is important to have as
much space as possible to compress the monolayer because the surface potential
of water/monolayer/air interface usually begins to change when the area/molecule
in the film is still quite large. Online display Digital display card displays on line status of desired parameter during an
experiment, e.g. surface pressure, dipping speed, barrier speed, etc. or any
other parameter selected by the user. Film balance Accurate measurement of the surface pressure and precise surface area control
system are crucial in fabrication of reproducible and defect free films. The
film balance is interfaced to a barrier driving system with a feedback circuit
for compression, expansion or for constant surface pressure operation modes. The
film balance uses Wilhelmy Plate method to measure the surface pressure. This
method incorporates a electronic micro balance and Wilhelmy Plate made of
platinum. Platinum is used because of its inertness and good hydrophilic
properties achieved by sand blasting of its surface. Platinum plate is easily
cleaned and durable in use. Only occasional calibration is needed and the
balance is electronically zeroed through the software. Surface area control The method of film compression is important in fabrication of reproducible high quality films. Several designs have been developed in search of ideal film compression. In these designs (bands, circular troughs and moving wall) the attempt to eliminate one specific problem have often lead to limitation of instruments versatility and reliability. *) KSV uses original well proven Langmuir trough design improved with symmetrical compression of the monolayer. This straight forward method have proven itself to be most practical with out compromising the high standard of your research work. The compression method is only as good as the mechanics moving it. The power of micro stepping motor is transmitted through a reduction gear box into a precision tooth belt driving the barrier holders. The barrier holders rides on a precision linear motion rail giving the barriers smooth and friction free movement. The barriers are attached to their holders by hand for easy removal. Moving wall compression, usable film area determined by width of substrate, moving wall scratches sides of substrate, no dipping of circular substrates. Band compression, band pushed outwards by film pressure, film collapse near corner post with condensed films, complex vibration causing mechanics. Circular trough, unstable pressure measurement due to uneven pressure distribution caused by the difference of film speed at inner and outer trough perimeter.
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