Sensing and computing are necessary components that human makes an attempt to understand and perceive the analog world by way of digital gadgets. The analog-to-digital converters (ADCs) discretize the analog alerts whereas the information bus transmits digital information between elements of a pc. With the rising of sensor nodes and the applying of deep neural networks, the power and time consumption limits the increment of knowledge throughput. In-sensor computing is a computing paradigm that integrates sensing, storage, and processing in a single gadget with out ADCs and information switch. In accordance with the mixing diploma, herein, we summarize 4 ranges of in-sensor computing within the subject of synthetic olfactory. Within the first degree, we present totally different capabilities are performed by utilizing discrete elements. Subsequent, the information conversion and switch are exempted throughout the in-memory computing structure with vital information encoding. Subsequently, in-sensor computing is built-in right into a single gadget. Lastly, multi-modal in-sensor computing is proposed to enhance the standard and reliability of the classification outcomes. On the finish of this minireview, we additionally outlook the usage of steel nanoparticle gadgets to realize such in-sensor computing for bionic olfaction.