BiPotentiostat

A BiPotentiostat is a potentiostat with two working electrodes. One electrode is the counter electrode and the other is the reference electrode. The two working electrodes can be operated and monitored exactly simultaneously. A Bipotentiostat is sometimes called a BiPot. The capabilities of the BiPot channel differ per instrument.

Each potentiostat has three types of electrodes:

Reference electrode: This is an electrode held at a known potential with high stability. Generally, it is grounded and held at 0 potential.
Working electrode: This is the electrode where the reaction of interest occurs
Counter or auxiliary electrode: This is the electrode that completes the circuit with the working electrode

The difference between a normal potentiostat and a BiPotentiostat is the number of working electrodes. A normal potentiostat has one working electrode, while a BiPotentistat has two.

BiPot module for PalmSens4

What do the working electrodes do in a BiPotentiostat?

Working electrode 1 performs one of the techniques listed on the bottom of this page, while working electrode 2 can have its own constant potential or follow the potential of working electrode 1. The reference electrode then only records the potential of the electrolyte and does not conduct current.

In this way, one can measure the working electrode or even the counter electrode separately. In the latter case, a potential offset can also be added.

Why use a BiPotentiostat?

Application examples:

Second electrode as blank or similar in the same cell for comparison
Detection of the reaction product of the disc electrode at the ring of a RRDE (Rotating
Ring Disc Electrode)
Polarization of the surface during scanning electrochemical microscopy (SECM)
Control of gate voltage transistors (ISFET)

What electrochemical techniques can be performed with a BiPotentiostat?

In BiPotentiostat mode, the PalmSens 4 supports the following four techniques:

The Sensit BT supports in BiPotentiostat-mode the following techniques:

What PalmSens instruments have a BiPotentiostat?

The Sensit BT.SNS comes with BiPot channel. The PalmSens4 is available with BiPot module for all PalmSens4 configurations. The BiPot module can be controlled with PSTrace for Windows and PStouch for Android.

BiPot specifications PalmSens4
dc-potential range	±5 V
dc-potential resolution	153 µV
dc-offset error	≤ 0.1% ±1 mV offset
accuracy	≤ 0.1%
current ranges	100 pA to 10 mA (9 ranges)
maximum measured current	i(WE1) + i(WE2) < 30 mA
current resolution	0.005% of current range (5 fA on 100 pA range) 0.0025% of 10mA range
current accuracy	≤ 0.1% at Full Scale Range all with additional 0.2% offset error
connection	Comes with a sensor cable with an additional (yellow) connector for WE2
power	Comes with additional USB Y-cable for extra power

BiPot specifications Sensit BT.SNS
Full dc-potential range	-1.2 to +2 V
Dynamic dc-potential range [1]	2.2 V
Compliance voltage	-2.0 to +2.3 V [2]
Maximum current	± 3 mA
Max. data acquisition rate	400k
Supports FRA/EIS	Yes

[1] The dynamic range is the range that can be covered during a single scan within the full potential range. For example; a linear scan can start at -1.5 V and end at 1.1 V or vice versa, covering 2.6 V dynamic range.

[2] The compliance voltage is the maximum potential between Working and Counter electrode and depends on the selected mode.