IDA Electrodes (Interdigitated Array)

Interdigitated Array (IDA) electrode is an electrode developed for electrochemical measurements to be performed in a very small quantity of the sample. IDA electrode could be applied for the detection and reaction analysis of the compounds in a small quantity of the sample. IDA electrode is a microelectrode pattern fabricated by using the lithography technology. The Electrodes are composed of 65 pairs. In each one of the pair has a function of the oxidation and reduction electrodes.

 

 

Features

・High sensitivity CV measurement
・Very small sample quantity for EC measurement                                
・Small and integrated
・Fast response
・Conductivity measurement

 

Schematic diagram of the electrode

 

Application example 

・HPLC measurement electrode
・Electrochemical measurement electrode
・Bio-sensor and chemical sensor electrode
・Chemically modified electrode
・Chemical reaction parameter monitoring electrode                             

 

Expanded diagram of the IDA electrode

 

CV measurement using Interdigitated Array Electrodes

IDA Electrode is a pair of band electrode combined and meshes with each other as a generator electrode and collector electrode, therefore it is possible to make an electrochemical redox cycle upon the electrode as showed in figure.
By occurring the redox cycle on electrode increasing electrolysis current to raise measurement sensitivity. In experiment using common electrodes to analyze a small quantity of sample solution, the sample will consumed and exhausted due to electrolysis. However using this Interdigitated array electrode, the oxidation-reduction reaction occur repeatedly so the sample solution will not exhausted.

redox-cycling reaction on IDA Electrode Redox cycle
keyword is diffusion and concentration slope

Substance to be oxidized/reduced into the sample solution is transported by diffusion to the electrode surface. Diffusion is the physical phenomenon of the molecular species transport from high to low concentrated region.

Interdigitated 65 pairs of generator/collector electrodes set off electrochemical RedOx cycling continuously as shown in Fig.1. This reaction significantly boosts sensitivity of the electrode. Furthermore, samples are preserved when Dual (Red-Ox) Mode is chosen - Not like as Single Mode eats up samples at measurements.

In single mode, the decrease of current response become very small because of the samples substance consumption due to the electrolysis.
Single mode
 
Compared with single mode, dual mode measurement has increased in 30 times the current value. Experimental data performed by using  CHI820B
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The voltammograms of ferrocene samples ((a),(c): 10 µL , (b),(d): 0.2 µL) using IDA electrode ((a),(b): Dual mode; (c),(d): Single Mode) are shown below. As they indicate, measuring mode makes obvious difference on their responses. Dual mode (a),(b) reinforce reduction current at collector electrodes with increase of oxidation current at generator electrodes, in addition, the current value is not affected by the sample volume, only depends on the concentration of the sample. At the measurement (d), comparing with (c), the current response is scarcely obtained, because the sample was consumed during the experiment, indicating that electrode response current of single mode is greatly dependent on the amount of sample solution.
Voltammogram by IDA Electrode

 

Size

IDA(Interdigitated Array) Electrode Substrate Dimension
Width 12.0±0.1 mm
Length 20.0±0.1 mm
Thickness 0.5 mm
Electrode Thickness
Au 90 nm
Pt
C 1.2 ± 0.1 μm
ITO 100 nm
Adhesive layer - Passivation membrane thickness
Ti approximately 10 nm
(∗only for Au and Pt)
Passivation membrane about 1 μm

 

IDA electrode expanded diagram

IDA(Interdigitated Array) Electrode
Catalog No. Description Width (µm) Interval (µm) Length (mm) Number of feet (pairs) Film thickness
012125 IDA electrode (Au) 10 5 2 65 90 nm
012126 IDA electrode (Pt) 10 5 2 65 90 nm
012127 IDA electrode (Carbon) 10 5 2 65 1.2 +/- 0.1 µm
012128 IDA electrode (ITO) 10 5 2 65 100 +/- 20 nm