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
Zoom Zoom
 
Image17-2.jpg
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
012129 IDA electrode (Au) 3 3 2 65 90 nm
012130 IDA electrode (Pt) 3 3 2 65 90 nm
012257 IDA electrode (Au) 2 2 2 65 90 nm
012258 IDA electrode (Pt) 2 2 2 65 90 nm
w/o passivation membrane
012259 IDA electrode (Au) without passivation membrane 10 5 2.5 65 90 nm
012262 IDA electrode (Pt) without passivation membrane 10 5 2.5 65 90 nm
012266 IDA electrode (Carbon) without passivation membrane 10 5 2.5 65 1.2 +/- 0.1 µm
012265 IDA electrode (ITO) without passivation membrane 10 5 2.5 65 100 +/- 20 nm
012260 IDA electrode (Au) without passivation membrane 3 3 2.5 65 90 nm
012263 IDA electrode (Pt) without passivation membrane 3 3 2.5 65 90 nm
012261 IDA electrode (Au) without passivation membrane 2 2 2.5 65 90 nm
012264 IDA electrode (Pt) without passivation membrane 2 2 2.5 65 90 nm
OPTION
011066 Cable kit for IDA electrode
011464 Ag/AgCl Ink for reference electrode (2.0 mL)

For Au and Pt, the thickness of the titanium adhesive layer is about 10 nm, resulting in a total thickness of 100 nm.

 

The handling of until measurement

For the high-sensitivity detection by redox cycle using IDA electrode, dual potentiostat is required.
In addition, CS-3A Cell stand to reduce the noise, and the coating of the reference electrode portion to have the stable reference potential, applying such as silver-silver chloride ink, are recommended.

Cable kit for IDA electrode movie

 

Handling precautions of IDA electrode

The IDA electrode is a very sensitive product. Here, some advice for the preservation and handling of IDA electrode will be described.

Attention for receiving the product

After receiving the product, it is recommended to test the insulation between the working electrodes using a tester.

Attention for opening the package

  1. When you will take out the electrode from the package, catch with the fingers at the edge of the glass substrate or pinch the glass plate carefully with tweezers. Glass substrate could break easily, so keep away from excessive force and strain.
  2. Do not touch the pattern area of the electrode directly. If you touch the pattern area, it could be peeled or break out.

Attention for cleaning before use

  1. Do not clean in ultrasonic cleaner.
  2. Do not clean the electrode with strong acid or base solution.
  3. Do not clean in ozone cleaner.
  4. Do not scratch the electrode surface to avoid the pattern area conductivity break down.
  5. If you want to clean the electrode with organic solvent, only rinse with acetone or ethanol. Do not immerse the electrode in an organic solvent for long time to avoid peeling of the electrode pattern and passivation membrane.

Attention in measurement

  1. The electrode can not be used in high and low temperature.
  2. Do not use the electrode in strong acid or base solution.
  3. Do not apply excessive oxidation or reduction potential.
  4. Physical or chemical modification of the electrode will be for your own responsibility. We do not guarantee the electrode characteristics after modification.
  5. This electrode is assumed as disposable. Reuse of the electrode is not recommended.

Attention in storage

If long-term storage, put the electrode in the case. Store the case in clean space such as desiccator, away from heat and moisture.

CAUTION

Any defects in the appearance (ex: pinhole on lead area, burr of glass) without any influence to the measurement, are not covered under warranty.


Technical Note

Experimental performance of the IDA electrode, with a small width (3 µm and 2 µm) is compared with the 10 um width IDA electrode.
Also, the collection efficiency was compared for the three types of the IDA electrodes.More fine IDA (Pt/Au) Electrode has been developed. Its 3 µm pitch working electrodes significantly increase redox cycle and allow researchers to perform ultra-sensitive measurement.  

IDA Electrode 3 µm

More fine IDA (Pt/Au) Electrode has been developed. Its 3 µm pitch working electrodes significantly increase redox cycle and allow researchers to perform ultra-sensitive measurement. 

                          IDA Au (3 µm)                                                                   IDA Pt (3 µm) 
IDA 3umIDA 3um 

We recommend to apply Ag/AgCl ink to a reference electrode in order to stabilize potential of the electrode. 

Technical data concerning IDA Electrode 3 µm

IDA Electrode Au 3um CV Curves - Modo individualFig. 1 - Accuracy

 A CV curve obtained by 3 µm IDA Electrode Au [A] mirrored that of 3 µm IDA Electrode Au [B], which  means both of the IDA Electrodes were produced very accurately.

  • Left: 3 µm IDA Electrode Au [A]; Right: 3 µm IDA Electrode Au [B]
  • Sample: ferrocene methanol (1 mM/ 0.5 M NaCl solution)
  • Mode: Single
  • Sweep Rate: 30 mV/s
IDA Electrode 3um Au CV Curve - Dual Mode

Fig. 2 - CV by Dual mode

  • Mode: Dual
  • Sweep Rate at G-Electrodes: 10 mV/s
  • Applied Voltage to C-Electrodes: -0.2 V 

Fig. 3 & 4 - Comparison of 3 µm IDA Au with 10 µm by Dual Mode

For 3 µm electrode, the limiting current of ferrocene methanol by CV Dual mode was 8 times as much as of the peak current by Single mode, while this ratio for 10 µm electrode was about 4. This means large increase of the redox cycle.

IDA Electrode 3um CV Curve -- Dual Mode 
Figure 3. 
IDA Electrode: 3 µm Au
Sweep Rate: 10 mV/s
IDA Electrode 10um CV Curve -- Dual Mode 
Figure 4. 
IDA Electrode: 10 µm Au
Sweep Rate: 10 mV/s
*Larger area in 10 µm IDA electrode gives the appearance as if its absolute current is larger than 3 µm of IDA
 

IDA Electrode 3um LSV Curve - Modo Dual

 

Fig. 5 - Capture Efficiency

Figure 5 shows a result of LSV Dual mode measurement. Its collection efficiency was proved to be 96.4% by our calculation from limiting current of Collector electrodes and Generator electrodes.

  • Method: LSV (Linear Sweep Voltammetry)
  • Mode: Dual
  • Sample: ferrocene methanol (1 mM/0.5 M NaCl solution)
  • Sweep Rate: 10 mV/s

Besides CV and LSV electrochemical techniques, our IDA electrode is available for various electrochemical measuring techniques such as chronoamperometry, normal pulse voltammetry, differential pulse voltammetry etc.
Researchers can obtain more insights by using IDA electrodes. 

 

IDA Electrode 2 µm

More fine IDA (Pt/Au) Electrode has been developed. Its 2 µm pitch working electrodes significantly increase redox cycle and allow researchers to perform high-ultra-sensitive measurement. 
IDA(Interdigitated Array) Electrode Au 2 um

Technical data concerning IDA Electrode 2 µm

A CV curve obtained by 2 µm IDA Electrode Au.

CV by Single mode

CV (Single) Using Au 2 um

  • Sample: 1 mM ferrocene methanol (0.5 M NaCl solution)
  • Mode: Single
  • Sweep Rate: 10 mV/s
 

CV by Dual mode

CV (Dual) Using Au 2 um

  • Sample: 1 mM ferrocene methanol (0.5 M NaCl solution)
  • Mode: Dual
  • Sweep Rate at G-Electrodes: 10 mV/s
  • Applied Voltage to C-Electrodes: -0.05 V
    Its collection efficiency was proved to be 97% by our calculation from limiting current of Collector electrodes and Generator electrodes.

 

Capture Efficiency

Compared with IDA Au 10 µm and 3 µm, the capture efficiency of the 2 µm is higher, 93% for 10 µm and 95% for 3 µm.
For 2 µm electrode, the limiting current of ferrocene methanol by CV Dual mode was 11 times as much as of the peak current by Single mode, while this ratio for 10 µm and 3 µm electrode were about 4 and 7.5, respectively. This means large increase of the redox cycle.