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The VersaSTAT LC Low Current Interface (LCI) is a specialized, research-grade accessory designed to augment the capabilities of VersaSTAT and certain PARSTAT series potentiostat/galvanostat systems. Its primary function is to enhance the resolution and accuracy of extremely small current signal measurements, extending the measurement range beyond the native capabilities of the connected potentiostat. The LCI is particularly useful for electrochemical experiments requiring the detection of attoamp-level currents, which corresponds to the flow of a very small number of electrons per second.
The LCI acts as a low current interface, plugging into the potentiostat/galvanostat system to provide an expanded range for current measurement and control. It is designed to facilitate ultra-low current measurements, resolving currents down to the attoamp (10⁻¹⁸ A) range. This capability is crucial for advanced electrochemical research where minute changes in current provide significant insights. The LCI system is comprised of three main components: an interface cable, the LCI main body, and four coaxial cell leads along with a ground lead.
The interface cable serves as the connection between the potentiostat/galvanostat's cell cable interface and the LCI main body. This cable is bi-directional, meaning either end can be connected to the LCI or the potentiostat, simplifying setup. The LCI main body houses the core electronics for low current amplification and processing. It features a cell cable panel with coaxial connections for the four cell leads (Working Electrode (WE), Working-Sense Electrode (SE), Reference Electrode (RE), and Counter Electrode (CE)) and a ground connection. Additionally, the cell cable panel includes pin-jack connections that can be used to connect the cell leads across a built-in 10 MΩ resistor. This internal resistor acts as a "dummy cell" for quality assurance, diagnostic purposes, or when no external cell is connected, allowing for system feedback and testing. The potentiostat interface panel on the LCI main body includes the interface connection to the potentiostat and a power LED. The cell cables themselves are coaxial and terminate in standard pin-jacks, which can accept various connectors like alligator clips, providing flexibility for connecting to different electrochemical cells.
The LCI system supports both current measurement and current control. For current measurement, it offers a wide dynamic range across multiple decades, from milliamperes down to femtoamperes, depending on the connected potentiostat. For current control, it allows for precise application of current across a similar range, with high resolution and accuracy.
Proper installation and calibration are critical for optimal performance of the LCI. The installation process involves connecting the interface cable to both the LCI main body and the potentiostat's front panel cell cable connector. It is essential to power off the potentiostat before connecting the LCI, as the potentiostat will only recognize the LCI upon boot-up. Once connected and powered, the system requires calibration.
The LCI system is designed for auto-detection of configuration changes, prompting the user for calibration when the VersaStudio software is launched after adding the LCI option. The calibration procedure is accessed through the software's "Tools>Options..." menu. During calibration, the system adjusts offsets to ensure accuracy. The process involves connecting specific cell leads together (WE, SE, and RE, then WE, SE, RE, and CE) as guided by the software. A crucial aspect of using the LCI for ultra-low current measurements is the environment. The software will prompt the user to confirm if the LCI is located in a Faraday cage, highlighting the importance of a shielded environment.
After calibration, a checkout procedure is recommended to verify proper operation. This involves connecting the cell leads to the LCI's built-in 10 MΩ dummy cell and performing a Staircase Linear Scan Voltammetry experiment using the VersaStudio software. The expected results, such as vertex currents and slope, confirm the system's functionality.
When measuring small current signals, several factors are important to consider. A Faraday shield is mandatory to block electromagnetic fields that can interfere with attoamp-level measurements. The LCI main body and cell leads should ideally be placed inside the Faraday shield, which must be properly grounded to the LCI and potentiostat chassis ground. Avoiding external noise sources such as electrical outlets, computers, motors, heating equipment, magnetic stirrers, and fluorescent lights is also crucial. The electrochemical cell itself should be designed to minimize noise, with stable lead and electrode placement to prevent microphonic and triboelectric effects. High impedance reference electrodes should be avoided as they can cause potentiostat instability and excessive voltage noise.
The LCI supports auto-current ranging, but users should be aware of the longer time constants associated with lower current ranges. If the hardware changes ranges during an experiment, data points collected during the transition may be flagged as suspect due to the time required for the system to settle. To mitigate potential oscillations when connected to capacitive cells, the VersaStudio software offers LCI Bandwidth Limits (Normal, Slow, Very Slow) which act as damping filters within the control loop. While "Auto" (Normal) is the default, users can adjust these limits to "Slow" or "Very Slow" if oscillations are suspected.
The VersaSTAT LC Low Current Interface is designed for optimum reliability and requires no periodic maintenance from the user. There are no user-serviceable parts inside the instrument. Opening the cover will void the warranty, emphasizing that any service or repair should be handled by the factory service department or an authorized affiliate.
For cleaning the instrument exterior, it is recommended to unplug the LCI from all voltage sources. Loose dust can be removed with a lint-free cloth, and remaining dirt with a lint-free cloth dampened in a general-purpose detergent and water solution. Abrasive cleaners should not be used. To prevent moisture from entering the instrument, only enough liquid should be used to dampen the cloth or applicator. The instrument must be allowed to dry completely before reconnecting the power cord.
In case of shipping damage, it is important to immediately notify Princeton Applied Research and file a claim with the carrier, saving the shipping container for inspection. Damaged equipment should not be operated, as its protective grounding might be compromised, and it should be tagged as unsafe.
Princeton Applied Research provides comprehensive support, including service, applications support, and various informational resources such as application notes, technical notes, and training materials. For service inquiries, customers are advised to contact the Customer Service Department or local representatives. If equipment needs to be returned for service, specific information such as model and serial number, user contact details, symptoms, and purchase order number (if not under warranty) is required.
General| Compliance Voltage | ±12 V |
|---|---|
| Potentiostat Compliance Voltage | ±12 V |
| Galvanostat Compliance Voltage | ±12 V |
| Frequency Range | 10 μHz to 1 MHz |
| Impedance Range | 10 mΩ to 1 TΩ |
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