UFI Model 1089 Family of Checktrodes™
Physiological recordings can be easily contaminated by noise and interference. In many cases, high electrode contact impedance is a big part of the problem. Noise often appears as 50 or 60 Hz "hum" from surrounding AC-powered electrical devices or as erratic spikes due to any motion of the lead wires. In virtually every case, these troublesome artifacts can be mitigated or completely eliminated by reducing contact impedance at the skin/electrode interface. UFI's Checktrode™ applied electrode contact impedance testers are designed to help accomplish this task.
UFI offers four time-saving and frustration-saving electrode contact impedance checking instruments. Our standard 1089 allows rapid evaluation of contact impedance when a few electrodes are used. For multiple electrode configurations, our 1089NP and 1089ES allow rapid, individual evaluation of large electrode arrays such as EEG caps. The 1089e is our latest offering -- and at an economical price too!
All 1089's are powered by a standard 9V battery. For the 1089, 1089NP and 1089ES, the decimal point on the LCD blinks when the battery is low, and all 1089's automatically shut down after 5 minutes.
Model 1089 MkIII Checktrode
The UFI model 1089 MkIII Checktrode supplies quick and easy evaluation of total contact impedance and offset voltage between two applied electrodes, and has been on the market for decades. The 1089 uses an AC excitation method which removes the effects of the polarization errors from the impedance reading. Leads with both the older .080" pin plugs as well as the newer .060" sheathed safety jacks are supported. The inclusion of a standard male snap allows electrode lead testing as well. A loaded battery test function is also provided.
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Model 1089NP Checktrode with Lead Selector
(tests each cap electrode against linked ear reference)
The Model 1089NP evolved from the 1089ES (below), but still includes the Lead Selector switch which provides rapid and painless checkout of your EEG Cap application. Whereas the 1089ES below is a general-purpose instrument, the Model 1089NP is designed for use with several specific electrode caps. These caps include the Brainmaster Discovery qEEG system cap, the NeuroPulse Systems qEEG cap, the Mistar Systems cap, and any standard Electro Cap or Comby Cap used with other 'qEEG' type systems. All these caps assume the use of a 'linked ear reference' approach, so the linked ear electrodes are the reference against which all of the other electrodes are individually checked.
For ease of use, the Model 1089NP rotary selection switch positions are directly labeled with electrode site names for the listed caps. A two-position TEST switch permits the two reference electrodes used with these caps to be first tested against each other. When good contact between them has been established, just flip the TEST switch to link these two reference electrodes, then check contact impedances between the individual cap electrodes and this linked reference.
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Model 1089ES Checktrode with Lead Selector
(tests each electrode against all other electrodes)
We designed this device a number of years ago, for customers who wanted to check contact impedances for more than just a few electrodes. The 1089ES includes a switch and associated circuitry to select up to 22 separate electrode leads (more are possible). The ES essentially checks each selected electrode against all of the other electrodes connected together. This allows the 1089ES to be used to check applied electrode contact impedance for multiple electrode arrays, including Cranial EEG "caps", rapidly and painlessly. The price of this device includes the DB-25 Female connector, supporting up to 22 electrodes. We can interface the 1089ES to your specific connector requirements, but there will be an additional cost for this. Contact UFI for more details.
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1089 general specifications
- impedance readout: 3 1/2 digit LCD display
- contact impedance range: 0-199 KOhm (custom ranges available)
- excitation frequency: 30 Hz (typical)
- typical excitation current: 10 uA p-p (constant current)
- calibration setting: 50 KOhm
- input connectors: 2 each 0.080" and 0.060" safety jacks and 1 male snap (1089)
- battery test load: 1 KOhm
- power switch: push-button on with auto-shutdown after 5 minutes
- rugged plastic case: 6" x 3.5" x 1.5" (Std 1089)
Model 1089e Economy Checktrode
Built on years of 1089 Checktrode service, this new design incorporates a microprocessor. A crystal-controlled 30 Hz sine wave is supplied to the electrode pair under test. Leads connect to the electrodes using the industry standard 0.060" safety jacks. The 1089e supplies a simple pass-fail LED indication for the contact impedance ranges of <5KOhm, <10 KOhm, <20 KOhm, <50 KOhm, and >50 KOhm. Simple, single-switch operation, with automatic power-down, further simplifies the use of this essential, 9V battery-powered instrument.
Model 1089e specifications
- range: 200 Ohms to greater than 50 KOhms
- typical excitation current: 10 uA p-p (constant current)
- rugged plastic case: 5" x 2.75" x 0.875"
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Published references to the Checktrode
