A mid-infrared gas sensor on the basis of a liquid-crystalline (LC) cell was developed. The main element in the sensor of the type proposed is a liquid-crystalline cell possessing marked dichroism of optical absorption in the mid-infrared spectral range. By fitting the absorbance and alignment parameters of the LC cell, it is possible to create the effect of the absorption edge shift when varying the magnitude of the electric field applied (2-10 V). This leads to some kind of wavelength modulation of an external optical radiation in the predetermined spectral area. By adding an appropriate light-emitting diode and photodetector to the system described, one can obtain a miniature scanning spectral instrument (sensor) of the new type without any moving parts and without usage of high voltages.