Projects
On this side some projects are described that differ in their execution to a normal corrosion setup ie they contain customer-specific extensions. They should function as a information sample for solutions that show what is feasible with our systems.
Customer-specific all-in-one solution of a corrosion setup
Rotating ring-disc-electrode / BI-Potentiostats and new measuring methods
Customer-specific all-in-one solution of a corrosion measurement setup
In the corrosion research beside known values such as current density and potential also the measurement of additional physical or mechanical values is demanded. Thereto standard solutions are often not sufficient. On hand of an actual example, we want to show the possibilities of today's technologies and modern tools.
We received a request concerning to a corrosion measurement setup from a manufacturer of metal pipes. In clarifying the requirements for this measurement setup it showed up that further measurement and control tasks have to be solved. The goal was to use the system for corrosion measurement and for other measurement tasks like for example:
- Temperature monitoring
- Strain measurement on metal pipes
- pH-value-measurement
- Solute oxygen in the electrolyte
Furthermore, a power source should be switched time- and temperature-depending. The power should reduce the wall thickness of a pipe. The resulting residual stress should be measured. The following overview image shows the solution worked out with the customer.
Illustration of an all-in-one measurement setup
The following components were selected for the corrosion measurement setup:
- Potentiostat IMP 88 PC
- Multifunctional measuring card
- Junction box for the adaptation of the measuring card and for signal conditioning
The junction box was fitted in addition to the standard equipping for the connection of a potentiostat also with a potential-separated module for the connection of a temperature sensor. For the strain measurement a Spider8 by HBM was chosen and for the measurement of pH-value, conductivity and solute oxygen a multifunction measuring device by WTW. As software our standard software for corrosion measurement and the program package VISUAL DESIGNER™ were used. With VISUAL DESIGNER™ all tasks were programmed that went beyond the corrosion measurement. A first application for the Spider8 (strain measurement), the control of the power source and the temperature monitoring was realized.
With the first application the customer obtained an instruction in the programming with VISUAL DESIGNER™ as part of the commissioning. Here he got to know a powerful graphical programming tool by reference to a known task so that he can quickly do changes himself that occur inevitably in the later process of the research project. The next image shows how such an application as block diagram may finally look like.
Application as block diagram
For the customer a powerful and flexible measurement setup was built that can always be adapted on new tasks easily and quickly.
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Rotating ring-disc-electrode / BI-Potentiostats and new measurement methods
For several decades now the Jaissle company is known as a manufacturer of rotating ring-disc electrodes in highest precision on the market.
Highest precision means:
- Concentricity of the electrode of approximately 1 / 100mm
- Stepless rotation speed control from 5 up to 4000 (6000) U / min
- Even after several 1000 hours of operation guaranted constant transition resistance in the Milli-Ohm range by a mercury current collector head (connection ring / disc)
Rotating ring-disc electrode
In addition to the ring-disc electrode the Jaissle company delivers a BI-potentiostat that is optimized for the specific requirements of this measurement method. The adjustable current range for both electrodes goes from 100nA to 100mA. Without electricity grid the device can operated with the built-in batteries for several hours.
During 1997 we received an enquiry about a BI-potentiostat including measurement system for the measurement of the conductivity of polymers and raster-electrochemical microscopy (SECM) with the following specifications:I
- Measurement of low currents in the nano- and picoampere range
- Scan speeds from 0,5mV to 2,5kV
- Current ranges from 10mA to 10nA for both sides of the BI-potentiostat ie by a current proportional 10V output signal for the current with a resolution in the lowest current range of 1mV = 1pA
- The by the operation of the two working electrodes in a measuring cell flowing equalizing / leakage current should be as small as possible (nA or pA)
BI-Potentiostat
After a thorough review of the enquiry we conceived a system consisting of the following components:
- BI-Potentiostat BI-PG 100 for low currents (power supply and battery operation)
- Current ranges from 100mA to 1nA for both measuring electrodes
- A possibly occurring equalizing / leakage current between the two working electrodes can be equilibrated
BI-PG 100 - BI-Potentiostat
Data acquisition, control und software
- Excitation and data acquisition by high speed cards with 12-Bit A/D- or D/A-converters
- Filters with voltage dividers and impedance converters for both analog outputs modification of the potential range and thus the increment of the D/A-converter
- Standard software ECHEMIE on MS-DOS™ for slow conductivity measurements (nowadays EcmWin on Microsoft® Windows™)
An interactive dialog was programmed that make the for the conductivity measurement necessary input and control elements available to the user.
Cyclic voltammogram
Thus in the both upper diagrams alternating each the both last cycles are displayed, in the lower diagram the conductivity (DI / DU) is displayed over the potential. The user can enter for both channels separate potentials and scan rates. Furthermore the polarization can be stopped or inverted at anytime during the measurement.
For the fast measurement processes an application was created with the program package LabView™ which allows the inputs of electrochemically known values. With the entered parameters the scan and the acquisition are started. After the measurement follows the display and storage of the data for further evaluation.
After completion of the project we found out that measurement devices and methods that are used for decades remain up to date and can even in alliance with computers and powerful software be used for entirely new research directions. Meanwhile it turned out that we also can expect more interesting application possibilities for this device combinations from fields of the biosensoric.
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Photoelectrochemical measurement
During 1999 we received an enquiry from a Swiss research institute referring to a photoelectrochemical measurement setup. The system should measure photoelectrochemical currents on oxidic semiconductors. It should consist of a sensitive potentiostat, a light source, a chopper, a monochromator, a shutter, a filter wheel and of course of a data acquisition and automation system. Furthermore a Lock-In amplifier should be used to acquire the relatively small photo currents. The Lock-In amplifier should be controlled via an IEEE 488 interface and a separate software that practically should run as a second task on the computer. In addition the control of the monochromator should be realized via the IEEE 488 interface.
A similar system was built up at the ETH in Zürich in the past and was used for similar measurements. At that time no distributor was available that could modify its software accordingly this was self-created with the help of graphical development tools.
After clarification and review of the requirements we came to the conclusion that the Lock-In amplifier could be replaced by an AC-voltage-amplifier in the potentiostat. The control of the monochromator was planned via the serial interface and integrated into our software EcmWin. Thereby an IEEE interface, the Lock-In amplifier and the necessary software could be used from the stock and that resulted in a significant reduction in costs.
Photoelectrochemical measurement setup
After the ordering we expanded our software EcmWin with a function module for photoelectrochemical measurements. This module controls the rotation speed of the chopper, the monochromator with filter wheel and the potentiostat. As alterable value for the measurement the wavelength of light in 5nm steps or the potential for the sample can be preset in 1 mV steps. The procedure can run manually or automatically over a defined range.
The potential of the sample, the photo current (AC and DC part / component), the pure AC part / component (over the additional AC-voltage-amplifier of the potentiostat) and the trigger signal of the chopper are aquired. The phase shifting between the trigger signal of the chopper and the AC-component of the photo current, the effective value and Imax - Imin of the photo current are calculated.
Photoelectrochemical measurement
Basically two measurement modes are distinguished:
- Normal photo current
- Transients measurement
By the normal photo current measurement in the upper graphic the trigger signal and the AC part / component of the photo current are displayed. In the lower graph of the DC and AC part / component of the photo current is displayed. The depiction / view takes place with 500 values per second for each channel. Therewith chopper frequencies up to approximately 50Hz can be good displayed. For higher frequencies the software can also be set to 1000 values per second. Out of the measured values practically all relevant variables can be mathematically determined. Compared with the data acquisition of a Lock-In amplifier here is more information about the signal curve / graph present ie the raw data is practically available.
During the transients measurement the chopper is halted and the wheel is positioned so that the light can fall unimpeded onto the sample. Then the data acquisition is started, the shutter is opened for a short time (5 to 10 seconds) and then closed again. The photo current of the turn on and off process is ascertained and stored.
Since the time of delivery not all specifications for the software were clear so we also supported the user with corresponding modifications in the period that followed. The aspiration is a flexible and easy to use measurement setup that makes all relevant functions for the photo electrochemistry available.
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At the first glace the following project does not have much to do with our main business the electrochemistry. However the enquiries out of the fields of the corrosion research are increasing in direction of decentralized data acquisition and monitoring. A recent example is the corrosion monitoring. The following described EDAS™ suits very good for such an application. It can not only be programmed for data acquisition tasks but just as well for control tasks. Thus, for example a potentiostat could be controlled via ethernet at any location. A parallel installed web camera would also make an additional visual check possible.
Measuring and monitoring of humidity, temperature, pressure and pH-value via ethernet
In the course of decentralized monitoring tasks the measurement data acquisition via networks is getting more interesting. Through the variety of the in- / output signals a cabling of sensors can usually only be made over short distances. The acquisition module must be installed as close as possible to the sources.
If an ethernet network is already installed in your company then the EDAS™ system from Intelligent Instrumentation GmbH® (IIG) will be the ideal solution for these tasks. EDAS™ means Ethernet Data Aquisition System. EDAS™ is available in two versions. As a pure digital module with 32 digital in- or output channels or as a mixed module with 16 analog inputs (single ended or 8 difference inputs), two analog outputs and 16 digital inputs or outputs (TTL level). The connection to the network takes place via a direct 10Base-T interface with TCP / IP protocol. As an application server EDAS™ provides in- and output functions to the connected clients in the network.
Principle setup of a system
Network-schema
Installation
EDAS™ is built-in in a housing with the dimensions of 152x141x39 mm. It can be used as a desktop case but can also be mounted on DIN rails for the control cabinet installation. It can also be installed as an OEM version in a 19-inch case. Therewith a signal conditioning can be realized using circuit boards in european format. EDAS™ requires a supply voltage between 15 to 28 VAC or 20 to 40 VDC.
The software platform
For the EDAS™-system drivers for MS-DOS™, Windows 3.1™, WINDOWS 95™, WINDOWS NT™ and UNIX™ are available. Moreover all features of VISUAL DESIGNER™ are supported. The module is configured with the EDAS™-syscheck program. Therewith it can be addressed in the network, the IP address, the subnet mask and possibly a gateway address have to be set.
EDAS1
EDAS™ can be programmed with VISUAL DESIGNER™ in an easy way. VISUAL DESIGNER™ is an easy to use application generator with a block-oriented development environment for PC-based measurement data acquisition. No programming skills are required. With the help of the development environment DIAGRAM™, the block diagrams (FlowGrams) are generated, the parameters for the functions are entered and the options for the runtime behavior are set.
EDAS2
The RUN™ program executes the application afterwards. When required the parameters can be changed in the runtime environment. Also in the runtime environment the user interface is defined. All visible objects on the screen can be moved and as well as size, color scheme, 3D-effects, font, color and style can be changed as desired. In the title bar any name for the application can be entered and the menu can be switched off as needed. Likewise a background graphic can be faded in and a copyright notice in the about-box can be inscribed. The program can be protected against unwanted changes when all the settings are done.
References
EDAS™ was delivered from the second week of October 1996. IPS has installed a first system in a bankhouse in Frankfurt am Main in the same month. There it is used for monitoring the temperatures of technics rooms.
EDAS3
To be prepared for more demands EDAS™ was built-in in a 19-inch case. The supply power provides a 24V switching power supply. 5V / 6A for switching functions are also available. The inputs / outputs of the EDAS™ module were conducted on a non-standard VME bus so that up to 10 cards in european format with diverse circuits as a plug-in assembly can be inserted. For the temperature acquisition PT100 sensors (1/3 DIN) with transmitter were built-in in a wall housing. The connection takes place via a two-wire cable.
As platform for the software development UNIX AIX 4.14™ or AIX 4.2™ was available. With the help of the EDAS™ software drivers some primary functions for reading the temperature values and for switching of contacts were realized. As superior program a shell script is working that retrieves the temperature values, verifies plausibility, verifies and stores Min and Max. If values lie outside the range then a message will be sent to the system administrator and an alarm lamp will be turned on.
After completion of the test phase the linkage to the system management system TIVOLI™ by IBM® was done.