ER818  Octal Contactless Conductivity System

ER818 Octal Contactless Conductivity System
ER818 Octal Contactless Conductivity System
  • Ready operation in an automated system
  • Low volume, low waste, no cross contamination
  • 100 µS/cm to 10 mS/cm conductivity range*
  • Pipette tips, melting point tubes, NMR tubes or capillaries


The ER818 was designed to allow the simultaneous contactless-conductivity measurement of up to 8 low-volume samples, with low wastage and zero cross contamination. This is not a standard product and it can be customized to meet customer’s application.

The system consists of a Control unit (ER815) and the ET128 Octal headstage. The ET128 headstage has eight recording reservoirs. It is manufactured to receive either pipette tips, melting point tubes, NMR tubes or capillaries.

The ER815 connects to the computer by USB. The 'virtual serial protocol' lets you use your own software such as LabVIEW or C#, or use WinWedge or HyperAccess to log the data directly into Excel.

The system uses a capacitively-coupled contactless conductivity measurement (C4D). This applies a high frequency signal to an excitation electrode which couples the signal to the sample. A detection electrode located some distance from the sample measures the resulting current, which is proportional to the sample conductivity. The measured quantity will depend on the physical dimensions of the test volume and its conductivity.

Temperature will play a significant role in accuracy of the measurements and the sensor temperature is measured and provided to allow temperature compensation to be applied to the conductivity measurement when necessary. A fan-forced ventilation system is provided to ensure that the sample temperature is as close to laboratory ambient as possible.

The conductivity of a solution inside a pipette tip was measured using the ER818 and an automated robotic system to place the pipette tips inside the ET128 Octal headstage; see the application note.

* conductivity range 100 µS/cm to 10 mS/cm (the range is determined by the inner diameter of the sample tube)


Specifications ER815 (with Multiplex Firmware)

  • Number of input channels: Up to 8 Multiplexed channels
  • Excitation frequency: Fast Square wave 10kHz to 2MHz
  • Excitation output: 5 V peak to peak
  • ADC: 1 differential channels 24 bit resolution (18 bits effective)
  • ADC output rate: Max 1000 samples per second per channel
  • ADC range FS: ±5 V
  • ADC offset error: < 100 µV
  • ADC Gain error: 0.1%
  • Analog Output (Rear panel BNC): CH 1 Delta K analog output selectable from ±5, +/-2.5 and +/-1Volt FS
  • Communication: USB 2 with virtual serial channel implemented.
  • Displays: Power LED. Blue = Power ON, Status LED. Green = On-line. Amber = sampling, Headstage module LED: Connected. Blinking = OverRange
  • Buzzer: Over-range buzzer sounds when head signal exceeds 3 V
  • Power requirements: 12 V nominal DC @ 10 W max 8 channels (Mains DC power adapter supplied)
  • Dimensions: 65 x 200 x 250mm (2.6 x 7.9 x 9.8 inches)
  • Weight: 1.8 kg (4.3 lbs)
  • Operating temperature range: 0 – 35˚C

Specification ET128

  • Sample tube dimensions: Maximum diameter 5.00mm, Minimum diameter 0.80mm, Minimum active length 30mm, Maximum Active length 65 mm
  • Sample tube position: 8 positions, 19mm apart
  • Head gain: From 0.4 µA/Volt to 40 µA/Volt selected to fit sample resistances
  • Output range: ±5 V (0 to 3 volts is the active range).
  • Offset range: ±5 V
  • Drift RTI: 2 µV + (6/Gain) µV/°C
  • Noise: <5 µV RMS measured with 50 Ohm input at Gain = 100 and 100 Hz filter
  • Frequency response: 0 to 1000 Hz
  • Filters: Fixed 1 Hz Low pass 3 pole Bessel
  • Multiplexer speed: 20 readings per second
  • System throughput: * conductivity and 1 Temperature channel per second
  • Temperature control: Fan assisted
  • Size: 150mm x 70mm x 95mm

System Specification

  • Conductivity range: From 100 µS/cm to 10 mS/cm
  • Active range: 100:1 with an error of 1% of FS
  • Variation between Channels: Measured at mid-scale after calibration <1% (will depend on positioning)
  • Noise: < 1: 1000
  • Frequency response: 0 to 1000 Hz
  • Filters: Fixed 1 Hz Low pass filter with Internal averaging
  • Multiplexer speed: 20 readings per second
  • System throughput: 8 Conductivity and 1 Temperature channel per second