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Transcranial Direct Current Stimulation (tDCS) is a form of non-invase neurostimulation that delivers a constant low level current to the brain through the use of electrodes placed on the scalp. This neuromodulation technique uses a steady current between 1 - 2 mA delivered through electrodes to targeted regions of the brain to modulate brain function. Using different electrode configurations, tDCS can be used to either excite or inhibit neuronal activity in the targeted region.
Headquartered in New York City, Caputron is the leading worldwide distributor of home, clinical and research neurostimulation technology, such as tDCS, TMS, CES and EEG. By partnering with world-class device manufacturers, we supply a range of excellent neurostimulation devices and accessories, such as Transcranial Magnetic Stimulation (TMS), Cranial Electrotherapy Stimulation (CES) and Transcranial Direct Current Stimulation (tDCS).
The High Precision Linear Current Isolator is an analog stimulus isolator that is optimized for the stimulation of extracellular and electrically excitable tissues. The LCI High Precision has a best in class DC accuracy.
The High Precision Linear Current Isolator is a linear current source that is optimized for the stimulation of extracellular and electrically excitable tissues. The output is capable of both source and sink the current, giving a full four-quadrant performance. Its high input impedance and high common mode voltage prevents a ground loop. With high bandwidth and high voltage slew rate, it can be used for high frequency stimulations or sharp waveforms. The LCI High Precision has a best in class DC accuracy. Optional charge balanced stimulation compensates the DC offset of function generators. The LCI High Precision includes a unique selectable feature that can remove DC offset of output, stimulates without causing harm to tissue or corroding electrodes. The LCI High Precision is easy to use and has a simple user interface and requires minimal maintenance due to an error detection system, internal calibration and advanced power management.
Input signal range is ±10 V with overvoltage protection. If the input exceeded this range, the indicator LED on the panel lights up. While the device is on, the input section is designed to show a very high impedance to output (10 GΩ || 220 pF) to prevent ground loop. A BNC connector carries the signal inside the device.
The output compliance voltage of the device is ±34 V. The output impedance of the device is more than 60 MΩ. The circuit is floating and the impedance between input and output is more than 1 GΩ. The maximum drivable load at 1 V input, is 33 kΩ for 1 mA/V and 330 kΩ for 100 µA/V gains.
The device is equipped with two different feedback networks, one provides 1 mA at output per 1 V of input command, and the other converts 1 V of input command to 100 µA of current at the output. Changing current gain does not cause any surge at the output. The following figure shows the absolute error of output in -1 mA to 1 mA range, with both conversion ratios.
Since the main application of the device is the stimulation of tissues, the output is applied to electrodes inside a solution. Connecting the current source to electrodes in saline cause DC voltage offset at electrodes, nevertheless, the tissue and electrodes are sensitive to even less than 1 V. “DC offset removal” monitors the output voltage and keeps the DC offset at 0 V during stimulation. The mechanism of removing DC offset is to subtract the DC value from command. “DC value” of the output signal is measured with an integrator with 0.1 s time constant.
Stimulating with metal electrodes inside saline, cause voltage offset at electrodes. The following figures illustrate the effect of using “0 VDC” and compare it with a normal output of a current source.
DC transfer characteristics describe the conversion of input voltage to the output current and the precision of the conversion in steady-state.
AC characteristics describe the process of output following the input. Bode plot is a good tool to show the accuracy of input-output conversion. The following plots show the output gain and the output phase with a 1 Vpp sinusoid as the input signal.
In order to have a charge-balanced stimulation, the device should sink the exact same amount of charge that is delivered to the target. Function generators or DACs which can be used to command the current source, have DC offset at the output. Even a small amount of offset at the device input, cause current leakage at the output, which will be accumulated after multiple cycles and cause electrode corrosion. This feature subtracts DC value from input signal. DC value of signal is driven by an integrator with a time constant of 0.1 s.
CAUTION: Only if charge-balanced stimulation is required, toggle the charge-balanced switch from “Normal” state to “Chrg blncd”.
Caputron Linear Current Isolator High Current uses high capacity Li-ion batteries. The lifetime of these batteries is around 1200 periods of charging and discharging, and they need the least amount of maintenance. Batteries can power the device on for more than 4 hours of continuous stimulation with 1mA output current. Beyond the rated lifespan of the battery, the capacity of them fall and the device needs to be charged more frequently. It is recommended to not use batteries beyond their rated lifespan. Batteries can be easily replaced by opening the device and inserting new batteries with the same specifications.
This device comparison table provides an overview of the specifications and features between the Caputron High Precision Linear Current Isolator, Caputron High Precision Linear Current Isolator, Caputron High Voltage Linear Current Isolator, Stanford Research Systems Model CS580 Voltage Controlled Current Source, A-M Systems Model 2200 Analog Stimulus Isolator and World Precision Instruments A395RC Linear Stimulus Isolator.
Below is a table containing detailed data of different parameters that can be useful for the assessment of each product. All products were new, calibrated and tested under the same exact conditions.
Device comparison highlights (1)
Scaled performance of highlighted parameters
Caputron Isolator Overview and Spectifications
Need to Return Your Purchase? It's Easy - Caputron Offers 90 Day Hassle Free Returns
Our return policy is simple. If you are not 100% satisfied with your purchase from Caputron you can return your item(s) within 90 days of purchase. If 90 days have gone by since your purchase, unfortunately we can’t offer you a refund or exchange.
(Returned devices must be in a new undamaged condition.) Merchandise returned damaged may not qualify for a refund.
Opened or used accessories such as electrodes, gel, saline, head straps, or other consumables are not eligible for a refund.
Packages are generally dispatched within 1-3 days after receipt of payment, though some exceptions may apply, and are shipped via UPS, DHL and USPS with tracking (when applicable) and drop-off without signature. If you prefer delivery by a different method, please contact us. Delivery with signature is available for an additional fee.
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International Customers Please Note: Any additional fees required by customs will be the responsibility of the buyer. We cannot control customs processing times in international countries. It is not uncommon for USPS First Class/Flat Rate parcels, or packages of any type, to get caught up in customs for weeks at a time. We highly recommend using UPS or DHL for international orders as they provide faster customs processing times and accurate tracking updates. We are not responsible for any added time due to customs. We will not be liable for, nor will any adjustment, refund, or credit of any kind be given as a result of any delay, misdelivery, or non-delivery. Items returned to us that were deemed undeliverable and are not damaged in any way are subject to partial refund for the cost of the merchandise minus the cost of shipping. At the discretion of both Caputron and the buyer, redelivery may be attempted for additional shipping costs determined prior to reshipment.
* When offered, free shipping is eligible only for the contiguous United States and does not apply to items that need to be shipped freight or for certain research items.
We use this device for our cell studies and it is incredibly useful. It provides many of the features found on the very expensive AM system models at a fraction of the price.
Read the datasheet and thought to myself it was too good to be true for this price. Bought this system to use in our lab and wow we were impressed. This device does everything it says it does and more. The engineers at Caputron have been very helpful in having in more features custom added for us. From now on this is the only device we will get for our lab.