High-Sensitivity Flexible Piezoresistive Pressure Sensor Using PDMS/MWNTS Nanocomposite Membrane Reinforced with Isopropanol for Pulse Detection.

Flexible pressure sensors with high sensitivity and good linearity are in high demand to meet the long-term and accurate detection requirements for pulse detection. In this study, we propose a composite membrane pressure sensor using polydimethylsiloxane (PDMS) and multiwalled carbon nanotubes (MWNTS) reinforced with isopropanol prepared by solution blending and a self-made 3D-printed mold. The device doped with isopropanol had a higher sensitivity and linearity owning to the construction of additional conductive paths. The optimal conditions for realizing a high-performance pressure sensor are a multiwalled carbon nanotube mass ratio of 7% and a composite membrane thickness of 490 µm. The membrane achieves a high linear sensitivity of -57.07 kΩ∙kPa-1 and a linear fitting correlation coefficient of 98.78% in the 0.13~5.2 kPa pressure range corresponding to pulse detection. Clearly, this device has great potential for application in pulse detection.

[Correlative analysis of cervical curvature and atlantoaxial instability].

OBJECTIVE: To investigate the correlation between the changes of cervical curvature and atlantoaxial instability. METHODS: The correlation between the changes of cervical curvature and atlantoaxial instability was retrospectively studied in 50 outpatients with abnormal cervical curvature (abnormal cervical curvature group) from January 2018 to December 2019. There were 24 males and 26 females in abnormal cervical curvature group, aged from 18 to 42 years old with an average of(30.62±5.83) years. And 53 patients with normal cervical curvature (normal cervical curvature group) during the same period were matched, including 23 males and 30 females, aged from 21 to 44 years with an average of(31.98±6.11) years. Cervical spine X-ray films of 103 patients were taken in lateral position and open mouth position. Cervical curvature and variance of bilateral lateral atlanto-dental space(VBLADS) were measured and recorded, Pearson correlation coefficient analysis was used to study the correlation between the changes of cervical curvature and atlantoaxial instability. RESULTS: Atlantoaxial joint instability accounted for 39.6%(21/53) in normal cervical curvature group and 84.0%(42/50) in abnormal cervical curvature group. There was significant difference between two groups(P<0.01). VBLADS in abnormal cervical curvature group was (1.79±1.01) mm, which was significantly higher than that in normal cervical curvature group(0.55±0.75) mm(P<0.01). Pearson correlation coefficient analysis showed that the size of cervical curvature was negatively correlated with VBLADS. CONCLUSION: Cervical curvature straightening and inverse arch are the cause of atlantoaxial instability, the smaller the cervical curvature, the more serious the atlantoaxial instability.