Ci Song

Real-time monitoring of local muscle response during acupuncture could reveal mechanisms underlying acupuncture and provide objective feedback to support more precise needle control. However, the small dimensions of acupuncture needles impose stringent constraints on sensor miniaturization and packaging. This study presents an ultraminiature pressure sensor integrated into the tip of a 450-μm-diameter acupuncture needle. The sensor measures 200 × 1250 × 50 μm³ and incorporates an elongated pressure-sensitive diaphragm. Wafer-level AuSn solder deposition and thermocompression soldering connect the chip to an ultrafine wire ribbon routed through the 230-μm-diameter needle lumen. A 1.3-μm-thick Parylene C coating provides electrical insulation. After coating, the sensor exhibited a sensitivity of 40.3 μV/kPa at a 3.3 V excitation, retaining 78.4% of its uncoated sensitivity. Characterization over 90–150 kPa absolute and 25–45 °C yielded a maximum nonlinearity of approximately 0.73% of full scale (FS). The coated sensor exhibited a maximum hysteresis of 2.52% FS. In vivo experiments at the Zusanli acupoint in rats recorded pressure variations during thrusting–lifting manipulation. These results demonstrate the feasibility of monitoring local muscle response during acupuncture and their potential to provide quantitative feedback for needle manipulation.

Precision deep-hole parts are extensively utilized across various sectors of industrial production, and their machining quality exerts a significant influence on numerous variables, such as fatigue limits, geometric precision, and product stability. On-machine measurement is a critical method to assess geometric features and guide the subsequent processing stage. This technique boasts substantial benefits, including immediacy, interactive capabilities, and widespread recognition within the metrology domain, particularly for the assessment of large-scale parts. As a crucial metric for appraising the machining quality of deep-hole parts, the measurement of roundness and axis straightness errors is paramount in ensuring the functional integrity of deep-hole products. Utilizing the wall thickness method, a multisensor integrated measurement system for these two categories of shape errors has been developed. This system employs an electromagnetic acoustic transducer (EMAT), an eddy current sensor, a laser interferometer, and a rotary encoder. Pertinent to this system, an uncertainty analysis model for roundness and axis straightness errors is devised. The effectiveness of the measurement system is verified by experiments.

Temperature can reflect vital activities, and researchers have attempted to guide Chinese medicine diagnosis and treatment by observing acupoint temperature changes. Integrating a temperature sensor at the needle tip enables in situ acupoint temperature measurement. However, the sensor needles for acupoint temperature monitoring designed in previous studies were fabricated by manually soldering thermistor beads and metal wires, making mass production difficult. In this work, using MEMS manufacturing technology, a flexible temperature sensor that can be integrated at the needle tip is proposed and can be mass-produced on silicon wafers. The sensor uses a Pt thermistor as the temperature-sensing element and has a slender flexible structure with dimensions of 125 μm width by 3.2 cm length. As the sensor is inserted into a hollow needle, the Pt thermistor is glued to the needle tip. In the temperature range of 30 °C to 50 °C, the fabricated temperature sensor has a sensitivity of 5.00 Ω∙°C⁻¹, a nonlinearity of ±0.39%FS, and a repeatability error of ±2.62%FS. Additionally, the sensor has been applied to in vivo acupoint temperature monitoring experiments in rats and demonstrated good performance, suggesting its promise for future research on acupoint temperature.