Reversible electrochemical mirror (REM) devices typically comprise a
conductive oxide mirror
electrode that is substantially transparent to
radiation of some wavelengths, a counter
electrode that may also be substantially transparent, and an
electrolyte that contains ions of an electrodepositable
metal. A
voltage applied between the two electrodes causes electrodeposition of a mirror deposit on the mirror
electrode and
dissolution of the mirror deposit on the counter electrode, and these processes are reversed when the polarity of the applied
voltage is changed. Such REM devices provide precise control over the reflection and transmission of
radiation and can be used for a variety of applications, including smart windows and automatically adjusting automotive mirrors. According to the present invention, measurements of the
sheet resistance of the mirror electrode in a REM device are correlated with the thickness of electrodeposited mirror
metal and can be used to monitor the reflectance of the device.
Sheet resistance measurements can be performed while the mirror state of the device is being switched if adequate isolation between the measurement and switching circuits is provided. This can be accomplished by use of external resistors or more sophisticated circuitry, or by taking
advantage of the relatively high
sheet resistance of the mirror electrode itself. Monitoring the reflectance of REM devices according to this invention provides significant cost and performance advantages.