The dissertation is dedicated to the development of a new acetone gas/vapour concentration determination method and sensor for medical (biomarker determination), labor, environmental and counter-terrorism protection purposes. Based on several studies, acetone concentration outside the norm may indicate a metabolic disease. Elevated acetone gas/vapour concentration can adversely affect working conditions and the environment; thus, determination of acetone gas/vapour concentrations is necessary. The solutions proposed thus far do not allow to detect low concentrations of acetone gas/vapour due to shortcomings in their operating processes. Within the dissertation, a literature review of existing sensors citing their advantages, disadvantages and operation principles was performed. The physical preconditions for creating a new sensor were studied. The methodology and tools used were developed as a part of the work. A method for estimating acetone vapour concentration using a new p-n opticaly stimulated sensor was realized. The results were presented and evaluated. As a result of the dissertation, conclusions and recommendations for further research were provided. For the first time, the possibility to reduce the acetone vapour concentration determination threshold to 0.636 ppm (applied to the sensitive area of 1 mm2) was demonstrated by realizing a method in which the new sensor for acetone vapour concentration determination was used. The dissertation is written in Latvian; contains an introduction, 7 chapters, conclusions, recommendations, list of references, 40 figures, 7 tables, 1 annex, 60 pages in total. List of references consists of 82 sources.