Dual Channel Differential Electrometer

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Electrochemical measurements with ion specific electrodes

  • Dual channel with very high input impedance
  • Separate outputs for Channel A, B and A-B (Differential)
  • Independent DC offset controls
  • Test port
  • Standby mode

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  • Measure changes in intracellular ion content electrochemically
  • Stable and drift free
  • Excellent amplification with low noise
  • Driven guard shield for reduced noise and stray capacitance
  • Set probe leakage current


  • Measure intracellular ion concentrations for K+, Ca2+, H+ and other species

The FD223a electrometer was designed specifically for use with intracellular ion selective electrodes fabricated using glass micropipettes and liquid ion exchangers.

The active head stages allow the researcher to locate the probes directly at the measurement site to minimize noise that would normally be picked up by longer cable runs. Driven guard shields cover the micropipette holders to further reduce the potential for interference from external sources of electromagnetic noise.

The FD223a is equipped with a test resistance port which is used to measure and adjust each probe for minimum leakage current. Each channel has a standby mode which clamps the head stage input voltage to zero, preventing extreme saturation or possible damage to the high impedance input amplifier.

Input Impedance > 1015 Ω, shunted by 0.5 pF
Input Capacitance 1 pF, nominal
Leakage Current 75 fA max
Gain 1.000 ± 0.1%
Output Resistance 50 Ω
Input Swing Voltage ±10 V
Rise Time (10 to 90%) 5 µs, small signal
Noise (0.1 Hz to 10 kHz) <100 µV p-p input shorted
Baseline Stability ±0.1 mV/day
Position Controls Range ±600 mV
Physical Dimensions Case: 8.8 x 21.0 x 17.5 cm (H x W x D)
Probe:12.7 x 65 mm (D x L), 1.8 m cable
Power 90-265 VAC, 50/60 Hz, 10 VA
Probe Handle 6.5 x 65 mm (D x L)
Shipping Weight 2.5 kg
Operating Conditions Equipment is intended to be operated in a controlled laboratory environment. Temperature: 0-40°C; altitude: sea level to 2000 m; relative humidity: 0-95%.

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