Ametek VersaSTAT LC Series User manual

VersaSTAT LC
Low Current Interface (LCI)
Hardware Manual
P/N 224186 Rev B

VersaSTAT LC Low Current Interface (LCI) Hardware Manual P/N 224186_0B
ii
TABLE OF CONTENTS
Figures..........................................................................................................iii
Tables ...........................................................................................................iii
Safety Instructions and Symbols...................................................................iv
Cleaning Instructions....................................................................................iv
1. Introduction ...............................................................................................1
1.1. About This Manual .................................................................................1
1.2. About the Low Current Interface (LCI) ......................................................1
1.2.1. LCI Interface Cable...........................................................................2
1.2.2. LCI Main Body .................................................................................2
1.2.3. LCI Cell Cables ................................................................................3
1.3. Inspecting Your New Instrument ..............................................................4
1.4. Maintenance, Service, and Support...........................................................4
2. Installation .................................................................................................5
2.1. Installation ...........................................................................................5
2.1.1. Connect Interface Cable to LCI Main Body ............................................5
2.1.2. Connect Interface Cable to Potentiostat Cell Interface ............................5
2.1.3. Connect Cell Cables to LCI Front Panel.................................................5
2.2. LCI Calibration ......................................................................................5
2.2.1 Calibration .........................................................................................5
2.3. LCI Checkout Procedure..........................................................................9
3. Measurement of Small Current Signals .....................................................11
3.1. Faraday Shield .................................................................................... 11
3.2. Avoiding External Noise Sources ............................................................ 12
3.3. Cell Design ......................................................................................... 12
3.3.1. Lead and Electrode Placement .......................................................... 12
3.3.2. Cell Construction............................................................................ 12
3.3.3. Reference Electrode........................................................................ 12
3.4. Experimental Properties........................................................................ 12
3.4.1. Auto Current Ranging ..................................................................... 12
3.4.2. LCI Bandwidth Limits ...................................................................... 13
4. Specifications ...........................................................................................15
4.1. Electronic Specifications ....................................................................... 15
4.1.1 System Performance....................................................................... 15
4.1.2. Power Amplifier.............................................................................. 15
4.1.3. Differential Electrometer.................................................................. 15
4.1.4. Current Measurement ..................................................................... 15

VersaSTAT LC Low Current Interface (LCI) Hardware Manual P/N 224186_0B
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4.1.5. Current Control.............................................................................. 15
4.2. Physical Specifications.......................................................................... 15
4.3. Standard Environmental Conditions ........................................................ 16
5. Warranty ..................................................................................................17
FIGURES
Figure 1. VersaSTAT LC Assembly........................................................................1
Figure 2. LCI-Potentiostat Interface Cable .............................................................2
Figure 3. LCI Cell Cable Panel (Left) and Potentiostat Interface Panel (Right) ..............3
Figure 4. LCI with Cell Cables Connected Across Internal Feedback (Dummy Cell)
Resistor .............................................................................................3
Figure 5. Cell Cables..........................................................................................4
Figure 6. Calibration Required Message ................................................................6
Figure 7. Calibration Procedure ...........................................................................6
Figure 8. Calibrate Message ................................................................................7
Figure 9. CE Not Connected ................................................................................7
Figure 10. Calibration Question Message Box.........................................................7
Figure 11. Connect Leads Calibrate Message .........................................................8
Figure 12. LCI Inside Faraday Box .......................................................................8
Figure 13. Calibration Complete Message ..............................................................9
Figure 14. VersaStudio Experiment Operational Screen ......................................... 10
Figure 15. K0269B Faraday Box ........................................................................ 11
TABLES
Table 1. Low Current Interface ............................................................................2
Table 2. Time Constants................................................................................... 13

VersaSTAT LC Low Current Interface (LCI) Hardware Manual P/N 224186_0B
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SAFETY INSTRUCTIONS AND SYMBOLS
This manual contains up to three levels of safety instructions that must be observed in order to avoid
personal injury and/or damage to equipment or other property. These are:
Safety Keywords:
DANGER Indicates a hazard that could result in death or serious bodily harm if the safety instruction
is not observed.
WARNING Indicates a hazard that could result in bodily harm if the safety instruction is not observed.
CAUTION Indicates a hazard that could result in property damage if the safety instruction is not
observed.
Safety Symbols:
Indicates Warning or Caution
Indicates Danger due to Electric Shock Hazard
Please read all safety instructions carefully and make sure you understand them fully before
attempting to use this product.
CLEANING INSTRUCTIONS
WARNING Using this instrument in a manner not specified by the manufacturer may
impair the protection provided by the instrument.
To clean the instrument exterior:
Unplug the instrument from all voltage sources.
Remove loose dust on the outside of the instrument with a lint-free cloth.
Remove remaining dirt with a lint-free cloth dampened in a general-purpose detergent and
water solution. Do not use abrasive cleaners.
CAUTION To prevent moisture inside of the instrument during external
cleaning, use only enough liquid to dampen the cloth or
applicator.
Allow the instrument to dry before reconnecting the power cord.

1
1. INTRODUCTION
1.1. About This Manual
This manual covers the installation and use of the VersaSTAT LC Low Current Interface (Figure 1) option
for the VersaSTAT series and some PARSTAT series of potentiostats/galvanostats. The VersaSTAT LC
is also referred to as the LCI option.
This manual does not discuss software installation or operation outside of the calibration procedure
(Section 2.2). For software operation, please refer to the VersaStudio™ operation manual.
Chapter 2 describes how to properly install, calibrate, and test the LCI option.
Chapter 3 discusses the measurement of small current signals with recommendations on shielding and
cell design.
Chapter 4 gives the physical and electrical specifications of the LCI.
Figure 1. VersaSTAT LC Assembly
1.2. About the Low Current Interface (LCI)
The Low Current Interface (LCI) is a plug-in, research grade option for the VersaSTAT®Series of
potentiostat/galvanostat systems (Table 1) that has been designed to enhance the measurement
resolution and accuracy of extremely small current signals.

VersaSTAT LC Low Current Interface (LCI) Hardware Manual P/N 224186_0B
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Table 1. Low Current Interface
PAR Potentiostat/Galvanostat Models that
Support the VersaSTAT LC Low Current Interface
VersaSTAT 3
VersaSTAT 4
VersaSTAT 3F
VersaSTAT MC
PARSTAT 4000
PARSTAT MC
The LCI consists of:
1) Interface cable that connects the cell cable interface of the potentiostat/galvanostat to the LCI main
body.
2) LCI main body.
3) Four (4) coaxial cell leads that connect from the LCI main body to the electrodes and/or cell
under test, as well as a ground lead.
1.2.1. LCI Interface Cable
The LCI-potentiostat interface cable (part number 223763, shown below) is a 1m long cable designed
specifically for the LCI. The cable is bi-directional, meaning that both ends are identical and may be
connected to either the LCI or potentiostat interfaces.
Figure 2. LCI-Potentiostat Interface Cable
CAUTION This cable is not to be modified from its original configuration.
1.2.2. LCI Main Body
The main body of the LCI is 19cm X 15cm X 4.5cm assembled. The cell cable panel (shown below-left)

Chapter 1: Introduction
3
has the coaxial connections for the four cell cables, as well as a ground connection. Also, pin-jack
connections for the cell cables are provided that connect across a built-in 10Mohm (10E7) resistor that is
to be used to provide feedback when the LCI does not have a cell to connect to, and/or it can be used as a
“dummy cell” for QA/QC or diagnostic purposes. The potentiostat interface panel has the interface
connection and power LED.
Figure 3. LCI Cell Cable Panel (Left) and Potentiostat Interface Panel (Right)
Figure 4. LCI with Cell Cables Connected Across Internal Feedback (Dummy Cell) Resistor
The WE cable connects to the W pin jack, the SE cable connects to the S pin jack, the RE cable connects
to the R pin jack and the CE cable connects to the C pin jack.
1.2.3. LCI Cell Cables
The cell cables (WE,SE,RE, and CE) and ground leads that connect to the LCI are approximately 40cm
in length, The cell cable terminate at the LCI end with a coaxial (BNC) connection, while the cell
connection end terminates in a standard pin-jack that can accept various connectors such as the included
alligator clips shown below.

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Figure 5. Cell Cables
1.3. Inspecting Your New Instrument
As soon as you receive your new LCI, inspect it for shipping damage. If any damage is noted,
immediately notify Princeton Applied Research and file a claim with the carrier. Save the shipping
container for possible inspection by the carrier.
WARNING If your instrument has been damaged, its protective grounding might now
work. Do not operate damaged equipment! Tag it to indicate to a potential
user that it is unsafe to operate.
1.4. Maintenance, Service, and Support
The LCI has been designed for optimum reliability and requires no periodic maintenance. There are no
user-serviceable parts in this instrument. Breaking the seal by opening the cover will void your warranty!
Contact the factory service department or the affiliate in your area if your unit needs service (see the
Warranty in Section 5 for more information).
Remember that our worldwide staff continues to support you after you have purchased your instrument.
We provide top quality service, applications support, and a variety of helpful information in the form of
application notes, technical notes, and training materials. For more information, visit our website at
www.princetonappliedresearch.com.
NOTE The SE (working-sense) and RE (reference) leads terminate in connectors
that will accept an additional pin input to make it easier to run three
electrode (WE shorted into SE) experiments and two electrode (WE shorted
into SE and CE shorted into RE) experiments.

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2. INSTALLATION
This chapter details how to install, calibrate, and test the LCI.
2.1. Installation
2.1.1. Connect Interface Cable to LCI Main Body
Connect the interface cable (Section 1.2.1) to the LCI main body (Section 1.2.2) and secure the cable to
the connector by tightening the screws until snug (do not over tighten).
2.1.2. Connect Interface Cable to Potentiostat Cell Interface
Connect the opposite end of the interface cable to the potentiostat front panel cell cable connector and
secure the cable to the connector by tightening the screws until snug (do not over tighten). The LCI
replaces the standard cell cable supplied with the potentiostat/galvanostat.
2.1.3. Connect Cell Cables to LCI Front Panel
Connect the four cell cables to the cell interface panel. The cables and panel on the LCI are labeled WE
(working lead), SE (working-sense lead), RE (reference lead), and CE (counter lead). The terminating
colors on the cell leads match those of the standard cell cable (WE=green, SE=gray, RE=white, and
CE=red).
2.2. LCI Calibration
The VersaSTAT LC Low Current Interface is designed to provide ultra-low current measurements beyond
the capabilities and specifications of the potentiostat to which it is attached. As such, calibration of the
potentiostat-LCI combination is required each time it is connected, and it is highly recommended that a
calibration be performed prior to each use to provide the best accuracy with each use.
2.2.1 Calibration
The VersaSTAT system was designed to auto-detect a configuration change, so after adding the LCI
option and launching the software, the following message will appear immediately upon starting the
software.
NOTE Once the LCI is connected and power applied to the system, a calibration
will be required, and the user will be prompted when the VersaStudio
software is launched to perform the calibration prior to use. Please see
Section 2.2 for calibration instructions.
NOTE Power off the potentiostat before connecting the LCI. Connecting the LCI
with power-on will not allow the potentiostat to recognize the LCI. Only at
boot-up (cycling the power on the potentiostat) will the LCI be recognized.

VersaSTAT LC Low Current Interface (LCI) Hardware Manual P/N 224186_0B
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Figure 6. Calibration Required Message
This message will appear after adding the LCI option to a system, as well as after removing the LCI
option.
The calibration procedure is located in the Tools>Options… menu within VersaStudio. Once the LCI is
properly connected and configured for the experimental conditions, select the “Calibrate Now” button.
Figure 7. Calibration Procedure
NOTE It is very important that the calibration be performed in the exact same
manner as the experimental settings. The lowest current ranges and current
measurements are affected by temperature fluctuations, vibrations, and
environmental sources of electromagnetic fields. Always calibrate the
system in the same experimental setup as your experiment requires.
Also, it is very important that the LCI and potentiostat be allowed to warm
up and reach temperature equilibrium. After power-on, wait a minimum of
20 minutes BEFORE performing the calibration.

Chapter 2: Installation
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After a few minutes of adjusting some offsets, the following window will appear:
Figure 8. Calibrate Message
The configuration in Figure 9 shows where the WE, SE, and RE are connected, but the CE is not. Once
connected, select “OK” to continue.
Figure 9. CE Not Connected
After a few more minutes of adjusting offsets, the following window will appear:
Figure 10. Calibration Question Message Box

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After indicating the presence of a Faraday cage or not, the following window will appear:
Figure 11. Connect Leads Calibrate Message
The photo in Figure 12 shows these connections. Note that this photo has the LCI inside the Princeton
Applied Research Faraday box, part number K0269B (door open on the K0269B for viewing). The ground
lead is also connected between the LCI and K0269B to properly ground the Faraday box to the same
chassis ground as the LCI and VersaSTAT.
Figure 12. LCI Inside Faraday Box
After completing the calibration, the following window will appear.
NOTE As the LCI is intended to measure ultra-low currents, it is highly
recommended that all experiments (and therefore calibrations) be
conducted in a shielded environment, such as a Faraday cage. Any
experiments where nanoamps and lower are to be measured, a shielded
environment must be used to block the electromagnetic fields that are
prevalent in most all laboratory settings.

Chapter 2: Installation
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Figure 13. Calibration Complete Message
The calibration will not take effect until the system is re-booted by cycling the power on the potentiostat.
2.3. LCI Checkout Procedure
As shown in Section 1.2.2, the VersaSTAT LC is equipped with a built-in 10Mohm resistor that can be
used as a “dummy cell” to perform a limited test of the system for proper operation.
To test the LCI with a VersaSTAT using dc voltage scan:
1. Connect the cell leads to the built-in 10Mohm dummy cell (The WE cable connects to the W pin
jack, the SE cable connects to the S pin jack, the RE cable connects to the R pin jack and the CE
cable connects to the C pin jack).
2. Select “New Experiment” in VersaStudio and choose the Staircase Linear Scan Voltammetry
action. Set the Initial Potential = -100mV, Final Potential = +100mV, Step Height=1mV, Step
Time=1s, Acquisition Mode=Average, Electrometer=Single Ended, E and I Filters = 10Hz (as
shown below). Once setup, select “Run” to acquire the data.
3. Once the data collection has finished, select all of the data points (Data>Select All) and perform a
Line Fit by selecting the Line Fit button at the top of thegraph.
4. The vertex currents should be +/-10nA, and the slope should be 1.0E-7 (the inverse of which is
10Mohm).
The PARSTAT4000 + VersaSTAT LC combination accesses additional lower current ranges than when
used with a VersaSTAT. These lower ranges have longer settling times, so the Checkout Procedure is
slightly different. If you use the VersaSTAT + VersaSTAT LC Check Out procedure on this combination,
data around 0 Amps will show a large measurement artifact (spike).
To test the LCI with a PARSTAT4000 using dc voltage scan:
1. Connect the cell leads to the built-in 10Mohm dummy cell. (The WE cable connects to the W pin
jack, the SE cable connects to the S pin jack, the RE cable connects to the R pin jack and the CE
cable connects to the C pin jack.)
2. Select “New Experiment” in VersaStudio and choose the Staircase Linear Scan Voltammetry
action. Set the Initial Potential = -100mV, Final Potential = +100mV, Step Height = 3.5mV, Step
Time = 7s, Acquisition Mode = Average, Electrometer = Single Ended, E and I Filters = 10Hz (as
shown below). Once setup, select “Run” to acquire the data.
NOTE No message is displayed after a successful calibration.
NOTE If “Failed Calibration” is reported by the software, double-check
connections, let the system stabilize for 30 minutes, then try again.

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3. Once the data collection has finished, select all of the data points (Data>Select All) and perform a
Line Fit by selecting the Line Fit button at the top of thegraph.
4. The vertex currents should be +/-10nA, and the slope should be 1.0E-7 (the inverse of which is
10Mohm).
Figure 14. VersaStudio Experiment Operational Screen
.

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3. MEASUREMENT OF SMALL CURRENT SIGNALS
This chapter describes the issues surrounding the measurement of small current signals to include proper
shielding and cell design recommendations.
3.1. Faraday Shield
The LCI and corresponding potentiostat system operate near the limits of current measurement. The LCI
system can resolve current in the attoamp (10-18) range. For perspective, 100aA represents the flow of
around 600 electrons per second!
A Faraday shield for low current measurements is mandatory. A Faraday shield is a conductive enclosure
that surrounds the cell. The materials can vary from a metal box or fine wire mesh, to a plastic case
covered in conductive paint. The conductive coating should be continuous on all sides of the cell
(including the bottom), and all parts operate as a single, conductive unit.
For the LCI, the best shielding will occur if the LCI main body and the cell leads are all placed inside the
Faraday shield, as the shield must be connected to the LCI ground. Note the photos below of the
Princeton Applied Research K0269B Faraday box. The box is made of steel with a few small openings for
cell cables or other leads. The box can be used in a vertical or horizontal position. In the photo to the
right, the LCI Main body has been attached to the wall of the K0269B using Velcro tape (not supplied).
Also note in the upper left corner above the cell is a grounding point to connect the ground lead from the
LCI to the Faraday shield (not connected in photo).
Figure 15. K0269B Faraday Box
NOTE The ring-stand and cell are not included with the K0269B Faraday box.

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3.2. Avoiding External Noise Sources
Always try to keep any electrochemical cell away from noise sources, regardless of current levels, but
especially for low current measurements. Some common sources of noise are:
•Electrical outlets and power strips
•Computers and their monitors
•Electrical motors
•Heating mantles or other heating/chilling equipment
•Magnetic stirring devices
•Fluorescent lights
Always place the cell as far from these devices as possible, and never place any of them inside the
Faraday shield.
3.3. Cell Design
3.3.1. Lead and Electrode Placement
The cell leads must not be moved during an experiment which is measuring small currents. Depending on
how sensitive the measurement, this includes eliminating even the smallest vibrations caused by the
cooling fan inside the potentiostat. Both microphonic and triboelectric effects can create false results
when the cable is moved during a measurement.
3.3.2. Cell Construction
Always ensure that your cell material and electrode materials are appropriate for the intended
measurements. A cell with impedance between the electrodes of 1010 Ohms cannot be used to make
measurements between electrodes at impedances of 1012 Ohms.
3.3.3. Reference Electrode
One of the most common problems with “cell noise” in electrochemical experiments in general is high
impedance reference electrodes and assemblies. High impedance reference electrodes can cause
potentiostat instability and excessive voltage noise generation. Always try to avoid:
Double junction Lugins (or bridge tubes)
Poorly conductive solutions inside Lugin
3.4. Experimental Properties
3.4.1. Auto Current Ranging
Although the VersaSTAT LC allows full auto-current ranging over the entire range from 20mA range down
to 4pA (80 fA if using the PARSTAT 4000) range, this can lead to some data points that are suspect due
to the long time constant associated with the lower current ranges. Any time the hardware “changes”
during a data point, the VersaStudio software flags that data point with “Code 2” in the Data View window
under the Comments section. As an example, the time constant associated with the 20pA current range
is 7s, so if a range change occurred to go from the 200pA to the 20pA current range, it would take around
7s for that range to measure the current accurately and allow the I/E converter to adjust properly. If the
experiment was collecting data at a rate of 1 point/second, there would be 6 points (provided the
experiment collect more than 6 points on the new, lower 20pA range) that would be suspect and labeled

Chapter 3: Measurement of Small Current Signals
13
as “Code 2” in the Data View. Below is a table of time constants associated with each range where the
TC>500ms.
Table 2. Time Constants
Current Range
Time Constant
20nA
900ms
2nA
2.1s
200pA
5s
20pA
7s
4pA
7s
3.4.2. LCI Bandwidth Limits
All potentiostats can become unstable and oscillate when connected to capacitive cells. Although
designed to minimize the onset of these oscillations, they can still occur in some experimental conditions,
and are most often manifested as excessive noise or “jumps” in the data and graphical output.
If an oscillation is suspected, one can use the LCI Bandwidth Limits in the VersaStudio software to try
and eliminate the oscillation. The “limits” are a range of damping filters (Normal, Slow, and Very Slow)
within the control loop of the VersaSTAT LC Low Current Interface that can help prevent oscillations
when performing experiments on capacitive cells. There is no recommended setting other than Auto
(which is “Normal”), and if oscillations occur, try stepping to “Slow” first, then “Very Slow” as a last resort.

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4. SPECIFICATIONS
4.1. Electronic Specifications
With the VersaSTAT LC option connected to the appropriate potentiostat, the following specifications are
in order. All other specifications not listed default to the connected potentiostat.
4.1.1 System Performance
•Minimum Current Range with VersaSTATs 4pA (4 x 10-12 A)
•Minimum Current Range with PARSTAT 4000 80 fA (80 x 10-15 A)
•Minimum Current Resolution 122 aA (122 x 10-18 A)
4.1.2. Power Amplifier
Maximum Current: +/- 200mA
4.1.3. Differential Electrometer
Input Bias Current < 200 fA at 25oC
Maximum Voltage Range +/- 10 V maximum
Input Voltage Differential +/- 10 V Bandwidth 700kHz (-3 dB)
Common Mode Rejection >60dB @ 100Hz, >50dB @100kHz
Input Impedance > 1014 Ω in parallel with < 200 fF, typical
4.1.4. Current Measurement
Ranges 12 decades, 200mA to 4pA (80 fA using the PARSTAT 4000) Accuracy (dc)
•2 μA to 200 mA < 0.2% full scale
•20 nA and 200nA ranges < 0.5% full scale
•200pA –4pA ranges < 1.0% full scale +/- 500fA full scale
4.1.5. Current Control
Applied Current Range +/- full scale per range
Applied Current Resolution +/- 1/32,000 x fullscale
Applied Current Accuracy +/- 0.5% of range, +/- 0.5% of reading
Maximum Current Range/Resolution +/- 200mA /10 uA
Minimum Current Range/Resolution +/- 4 pA / 122aA
4.2. Physical Specifications
Weight 500g (1.1 lbs.), not including cable.
Dimensions 14.6 cm W x 19.1 cm D x 4.54 cm H (5.75 in x 7.5 in x 1.75 in)

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4.3. Standard Environmental Conditions
This equipment is designed to meet or exceed the requirements of the following standards:
•LVD: EN61010-1:1993, Amendment 2
•EMC: EN61326: 1998 Emissions
•EN55011:1991, Group 1, Class A
Immunity:
•IEC 61000-4-2:1995, ESD
•IEC 61000-4-3:1995, EM field
•IEC 61000-4-4:1995, Burst
•IEC 61000-4-5:1995, Surge
•IEC 61000-4-6:1995, Conducted RF
Operating Temperature: 10oC to 50oC
Humidity: maximum 80% non-condensing
Protection against ingress of water, IPX0