To improve the privacy and security of medical images， a joint algorithm integrating YOLO image recognition and chaotic system-based image encryption is proposed. First， the optimal recognition model is determined through comparative experiments on multiple versions of the YOLO model. Then， simulation experiments are conducted on the proposed encryption algorithm and the recognized images to generate encrypted images. The feasibility of the algorithm is verified by encrypting the recognized target images. Meanwhile， common images are selected for encryption processing and compared with other encryption algorithms. The performance of the algorithm is verified by combining methods such as histogram test， correlation test， NPCR and UACI tests. The results show that the proposed algorithm can effectively realize the coordinated operation of medical image recognition and encryption， and has high privacy protection security and reliability.

To meet the demand for pressure monitoring in high-temperature environments， this study designs and demonstrates an all-SiC piezoresistive pressure sensor based on a 4H-SiC epitaxial layer. A parameterized finite-element model is established in COMSOL to compare the stress and deflection responses of circular and square diaphragms under 0-3 MPa loading， leading to the selection of the circular-diaphragm design. Electro-thermo-mechanical coupled simulations are further conducted to evaluate the output characteristics over a wide temperature range of 0-500 ℃. A hybrid diaphragm fabrication process combining femtosecond-laser pre-machining with ICP etching is proposed to enable efficient thinning of the thick substrate while improving surface quality. The test results show that the sensor exhibits a good linear output in the range of 0-3 MPa， with a full-scale output of 44.554 mV， a normalized sensitivity of about 1.49 mV/（V·MPa）， a maximum deviation of 4.19% from the linear fitting curve， and a hysteresis error as low as 0.0045%FSO. These results indicate that the proposed structural design and composite fabrication process can meet the requirements of high-temperature pressure measurement and provide a reference for the design and fabrication of all-SiC high-temperature pressure sensors.

Aiming at the problems of low sensitivity and long response time of non-dispersive infrared CH₄ gas sensor, a CH₄ gas sensor based on photoconductive principle is designed. The sensor is mainly composed of PbSe photoconductive infrared detector, signal processing circuit, light source driving circuit and light path gas chamber. By analyzing the relationship between gas concentration and detector output signal, the concentration output relationship equation is fitted to realize the detection function. Through experiments, gases with different concentrations are detected at room temperature. The results show that the output error, minimum detection limit, minimum response time and other parameters of the sensor are good, and the gas can be effectively measured in the range of 1000 cm³/m³.

Aiming at the problem that the traditional dynamic element matching(DEM) method needs more hardware resources, a second-order error feedback noise-shaping SAR ADC is designed. The design uses segmented capacitors to reduce the size of DAC array and the capacitance of error feedback loop, and reduce the area of the whole circuit. On this basis, a DEM method applied to segmented capacitor array is formed, which reduces the influence of capacitor mismatch on performance parameters such as signal-to-noise-distortion ratio(SNDR) at the cost of fewer additional circuit components. The simulation results show that the designed noise-shaping SAR ADC can achieve 70.9 dB SNDR with an 8-bit capacitor array with a capacitance mismatch of 0.3%, and the required area is only 0.019 mm².