Electrochemical Characterization of the Microfabricated Electrochemical Sensor‐Array System

Abstract

Microfabrication technology has been used to prepare a microchip sensor‐array with six sets of platinum electrodes. Chromium/platinum (10 nm/100 nm thick) were sputtered on a borosilicate wafer and patterned by wet etching method. The electrodes were designed with working electrode area of 700×400 μm in the middle and a 200 μm wide and 2600 μm long counter electrode surrounding it from three sides in a U‐shape. The connection pads (1000×1500 μm) were located at the edge of a sensor‐array chip. Silicon wafer was etched through to form holes with slanting side walls for immobilization cavities. The silicon and the borosilicate wafers were adhesion bonded with SU‐8 epoxy resin. The cyclic voltammetry and electrochemical impedance experiments were carried out in a three‐electrode electrochemical system to characterize the fabricated sensor‐array chip. The results show that the current density depends on the electrode potential sweep rate ν. Also, current density depends on the concentration of potassium hexacyanoferrate(III). At slow potential sweep rates (ν≤0.01 V s−1) the steady‐state signal is achieved and the electrodes behave as micro‐electrodes. Such an array is a promising candidate for fast and simple biochemical oxygen demand (BOD) measurements.

Understanding the Influence of the Electrochemical Behavior of Potassium Hexacyanoferrate(II/III) on Acetonitrile/Water Binary Mixtures: An Experimental and Molecular Dynamics Study

“…Potassium hexacyanoferrate is a well-known electroactive probe, and its redox process is frequently used to evaluate electrode performance in voltammetry. ,, Cyclic voltammograms of 10 mmol L –1 potassium hexacyanoferrate­(III) solutions were registered at x ACN varying from 0.0 to 0.65. The experiments performed at a higher content of ACN were not carried out due to the formation of precipitate and phase separation.…”

Electrooxidation of Hexacyanoferrate(II) Anions and Electroreduction of Oxygen in the Microfabricated Electrochemical Sensor-Array System

“…The preparation of the sensor array microchips is described in our previous paper in detail (11). Shortly for fabrication silicon wafers (100 mm diameter and thickness of 500-525 µm) and borosilicate wafers (Pyrex glass with same dimensions as silicon wafers) were used.…”

“…The experimental value 0.16 A m −2 mM −1 is in relatively good agreement with the theoretical calculated value. The slope value is greatly overestimated with models using other geometries (10 mV s −1 ): microdisk (5 times), microband (50 times), and infinite plane (6 times) and therefore these models cannot be used (11).…”

“…It is based on deposition, lithography and etching steps using materials like silicon, polymers, metals and oxides that enable the fabrication of wells, reactors, channels, and electrodes with dimensions in the micrometer to millimeter range. Microfabrication technology also enables batch-fabrication, which leads to production of inexpensive sensors and even, disposable, maintenance-free sensors (7).…”

“…Environmental monitoring and analysis is widely used field for application of sensor-arrays in samples such as drinking, ground, sea and industrial waters where reliable and robust analytical techniques with low detection limits are required (6). In addition, it has been shown that by applying various multidimensional data analysis methods to sensor-array data it is possible to extract more information from measurement data (7,10).…”