Intracellular Electrometer (IE-251A)

Intracellular Electrometer (IE-251A)

The IE-251A is a moderately priced intracellular electrometer complete with current passing capability and incorporating the same basic design as the more costly IE-210.

  • Fixed gains of x1 and x10
  • Capacity Compensation neutralizes input capacitance for up to 50 pF
  • Junction potentials of up to ±200 mV are nulled with the DC Position control
  • Electrode Test provides convenient electrode resistance check
  • Push button operated Buzz produces oscillations at pipette tip to facilitate cell impalement
  • Convenient Probe Test port permits fast check of amplifier performance

Item# Description U.S. List Price Quantity
64-0090 IE-251A Intracellular Electrometer
64-0964 ESP/W-F10N Electrode Holder, Straight 1.0mm for IE-210/251A
64-0965 ESP/W-F12N Electrode Holder, Straight 1.2mm for IE-210/251A
64-0966 ESP/W-F15N Electrode Holder, Straight 1.5mm for IE-210/251A
64-0967 ESP/W-F20N Electrode Holder, Straight 2.0mm for IE-210/251A
64-0043 2510 Replacement Headstage for IE-251A Electrometer
460-7013 (BNC-6) BNC to BNC cable, 6 feet (Pomona)
460-7032 (BNC-2) BNC to BNC cable, 2 feet (Pomona)
64-2300 (TH-1) Replacement handle with 6-32 female thread (fits Warner headstages)
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The IE-251 is a low cost version of our popular IE-210 intracellular amplifier. The important features required for low noise, drift free recording from glass microelectrodes have been retained in this lower cost model. The IE-251A is easy to use and is an excellent choice for the budget-conscious researcher or student teaching lab. It features a very small active headstage, essentially the same as used with the more costly IE-210. Epoxy-sealed construction affords maximum resistance to saline corrosion. Its small size and low mass permit easy mounting in a micropositioner. The electrode holder supplied connects directly to the probe input.

Current Injection

The injection circuitry of the IE-251A allows simultaneous stimulation and recording through microelectrode resistances up to 1000 MΩ in two ranges. Voltages at the Stimulus Input are converted to constant currents applied to the electrode. The steady state and transient components of the current injection artifact are nulled with the DC and transient balance controls. The corrected signal is viewed at the single-ended bridge output. Electrode resistance is read from the DC balance ten-turn dial.

Overdrive Indicators

Two visual indicators call attention to overload conditions:

  • Input Overdrive is illuminated whenever the probe input voltage exceeds ±1 V, caused by either excessive current through the microelectrode or an open circuit (open or blocked electrode)
  • Current Overdrive warns of excessive voltage (>50 V) applied to the Stimulus Input

The IE-251A is supplied with a probe. However, an electrode holder must be purchased separately based on your glass outer diameter. Also, specify line operating voltage if other than 100-130 VAC. Typical electrode holder options are listed below with pricing information.

Amplifier Input Impedance 1011 Ω shunted by 0.5 pF
Noise Level (0.1 Hz to 10 kHz)*

25 µV p-p input shorted

250 µV p-p, 20 MΩ at input

Output Resistance 100 Ω
Gains x1, x10
Rise Time (10 to 90%) 10 µs measured with 20 MΩ resistor
Capacity Compensation 0 to 50 pF
Probe Input Voltage Range ±1 V
DC Positioning Range ±200 mV referred to input
Leakage Current Adjustable to zero
Electrode Test 1 mV/MO
Buzz Amplitude variable 0-15 V
Frequency variable 100 Hz to 10 kHz
Current Injection Bridge Balance Ranges 0 -100 MΩ and 0 -1000 MΩ
Current Injection Limit ±1 V divided by electrode R or 0.5 µA, whichever occurs first
Stimulus Input Resistance 3.3 kΩ
Maximum Stimulus Input ±50 V
Bridge Bal. Output Resist. 100 Ω
I Monitor Output Resist. 1 kΩ
I Monitor Output Scale Factor 1V = 50 nA
Physical Dimensions Case Size: 12.5 x 20.3 x 25.4 cm (HxWxD)
Probe: 9.5 x 65 mm (D x L) with 1.8 m cable

100 -130 or 220 -240 V, 50/60 Hz, 20 VA

Probe Handle

6.5 x 65 mm (D x L)

Shipping Weight

4.5 kg


Two years, parts & labor

  1. Mechanisms of recurrent ventricular fibrillation in a rabbit model of pacing-induced heart failure
    Ogawa M, Morita N, Tang L, Karagueuzian HS, Weiss JN, Lin SF, Chen PS
    Heart Rhythm. 2009 Jun;6(6):784-92. Epub 2009 Feb 12
  2. Perturbation of the activity of a single identified neuron affects long-term memory formation in a molluscan semi-intact preparation
    Lowe MR, Spencer GE
    J Exp Biol. 2006 Feb;209(Pt 4):711-21
  3. cAMP-induced changes of apical membrane potentials of confluent H441 monolayers
    Lazrak A, Matalon S
    Am J Physiol Lung Cell Mol Physiol. 2003 Aug;285(2):L443-50. Epub 2003 Apr 18
  4. Bending the MDCK Cell Primary Cilium Increases Intracellular Calcium
    Praetorius HA, Spring KR
    J Membr Biol. 2001 Nov 1;184(1):71-9
  5. Mechanisms underlying presynaptic facilitatory effect of cyclothiazide at the calyx of Held of juvenile rats
    Ishikawa T, Takahashi T
    J Physiol. 2001 Jun 1;533(Pt 2):423-31
IE-251A (050816.1).pdfIE-251A User's Manual