Technological principles of motion parameter transducers based on mass and charge transport in electrochemical microsystems

Abstract

An electrochemical transducer (ECT) with the operation principle based in the phenomenon of molecular-electronic transport is a set of electrodes placed into the solution of electrolyte (Fig. 1).As a rule, a solution used contains a high concen tration of background (not participating in the elec trode reactions) electrolyte with a slight additive of the active component for charge transfer through the liq uid/metal interface on the electrode surface. It is known that in this case, it is sufficient to consider only the fluxes of the active component to account only for diffusion and convective transport to calculate the current in the system. The role of the background elec trolyte is limited to screening the electric field in the liquid and thus suppression of migration charge trans port. Operation of the sensor is based on the fact that the rate of the electrochemical reaction on the elec trodes is much higher than the rate of supply of the reacting substances.The principle of ECT operation can be easily explained using the approximation of planar perme able (for liquid but not the charge) electrodes first developed in [1]. When electric voltage is applied to the system, electrochemical current appears (the so called "background current") independent of the presence of mechanical motion (Fig. 2a). In this case, electrochemical reactions cause the development of the concentration gradients of the solution compo nents and charge transport in stationary electrolyte occurs through diffusion of ions from one electrode to another.Abstract-The most important advantage of motion parameter transducers based on mass and charge trans port in electrochemical systems is exceptionally high rate of mechanical signal conversion to electric current. Devices of this class are based on the principle of diffusion charge transport under the conditions of forced convection appearing as a result of external acceleration. This work shows the possibility of development of modern high-technology devices based on an electrochemical transducer developed using up-to-date microelectronic technologies.

Molecular Electric Transducers as Motion Sensors: A Review

“…Typically, MET uses concentrated iodine-iodide electrolyte containing potassium iodide (KI) or lithium iodide (L i I) and a small amount of elemental Iodine (I 2 ) [20]. In the presence of iodide, iodine turns into a soluble compound, tri-iodide, as follows [20]: $I_2+I^{-}\to I_3^{-}$when the electrodes are biased and thus current passes through the electrochemical cell, the following reversible active electrochemical reactions occur on the electrodes:…”

“…Although each electrode current is non-linear with respect to fluid velocity, the combined output of both cathodes is linear for a very wide range of fluid velocities. Mathematically, the sensor's output current is given by [20]: $I_{\mathit{\text{out}}}=I_{C2}-I_{C1}= Dq(\underset{S_{C2}}{\oint }\left(\mathrm{\nabla }c,\mathbf{n}\right)d{S}_{C2}-\underset{S_{C1}}{\oint }\left(\mathrm{\nabla }c,\mathbf{n}\right)d{S}_{C1}$where I C1 , I C2 are the currents through the surface of the corresponding cathodes, S C1 , S C2 are the surface areas of the corresponding cathodes.…”

“…This structure is studied in [20] and it is shown that it has promising performance comparable with ring electrodes in open holes when the device size is reduced to micro-scale. This planar electrode structure is very easy to fabricate with standard photolithography technology, offering outstanding precision and repeatability.…”

Electrochemical Seismometers of Linear and Angular Motion

“…Until recently, the instruments of this kind were used almost exclusively for measurements in the low-frequency domain. However, the developments of recent years (Krishtop et al 2012) have made it possible to produce the devices with an upper operating frequency that exceeds the values typical for most geophones. The experience learned from the development of such sensors indicates that the optimal operating characteristics are attained when MET-based sensors are equipped with an electrodynamic negative feedback mechanism.…”

The fabrication of electrochemical geophone based on FPCB process technology

“…Electrochemical motion sensor substantially originated from 1990s, which should be attributed to the continuous research work from V. A. Kozlov and V. M. Agafonov et al [2][3][4][5][6][7] The practical advantage of the electrochemical motion sensor is the ability for providing a high conversion factor with a very simple and suitable mass production signal converting system [7], which makes it possible for increasing the bandwidth by the mean of signal process or feedback control technology although the sensitivity for motion will be lost a little. So, there is a great potential for electrochemical motion sensor designed as geophone.…”