particularly important for the detection of physiological signals. To improve the high sensitivity performance of pressure sensors, some researchers have designed special microstructure shapes-that is, pyramids, [16][17][18] ciliated microarrays, [19] inclined micropillars, [20] and convex microarrays. [21][22][23][24] Luo et al. designed a tilted micropillar structure to act as the dielectric layer of a pressure sensor using photolithography technology, [20] and improved the sensitivity of the pressure sensor by 0.42 kPa −1 through bending deformation of the tilted micropillar. Xiong et al. sputtered a gold layer microarray on a film to form a polydimethylsiloxane-gold (PDMS-Au) electrode, and placed a polyvinylidene difluoride (PVDF) film in the middle layer of the electrode to form a pressure sensor with a sandwich structure and a sensitivity of 30.2 kPa −1 . [25] Guan et al. converted natural wood into graphene-oxide-modified flexible wood through a sawing process and chemical treatment, obtaining an environmentally friendly wood pressure sensor with a sensitivity of 1.85 kPa −1 . [26] Sun et al. proposed a flexible fish-scale structure based on a PDMS/carbon nanotube (CNT) composite material, [27] the tactile electronic skin sensor developed with a high sensitivity of 12.1 kPa −1 . Although a variety of microstructure designs have improved sensor pressure sensitivity, when dealing with high pressures (>50 kPa), a single microstructure design can cause a pressure sensor to suffer from limited or saturated pressure response. This is because high-pressure sensors are not considered in the design of multi-level structures to increase the pressure test range of a sensor. [28] Moreover, they require expensive equipment and complex manufacturing processes. Consequently, pressure sensors that are designed with high sensitivity and undergo pressure testing over a wide range will become an important research topic for future studies.In this study, we used PDMS as a flexible carrier and added several conductive materials-such as carbon black (CB), CNTs, and nano-copper powder-to prepare conductive inks suitable for 3D printing. [29][30][31] To detect a wide range of pressures, the inclined-tip cone array of a flexible pressure sensor's conductive layer was designed as a three-layered structure with a stepped height. Inclined cone arrays of different heights produced more sensitive bending over a low-pressure detection range. UnderThe high sensitivity and portability of flexible pressure sensors have attracted widespread attention from researchers owing to their potential use in health monitoring and exercise detection applications. However, to improve the performance of pressure sensors, a special microstructure-shaped design is necessary, which usually requires a complicated manufacturing process. In this study, the use of 3D printing technology is proposed to develop a polydimethylsiloxane-based material along with several conductive materials-carbon black, multiwalled carbon nanotubes, and copper mixed conductive in...

ObjectiveRecent controversial evidence suggests that maternal diabetes may increase the risk of attention deficit and hyperactivity disorder (ADHD) in offspring. To examine this potential association, a systematic literature search and meta-analysis was performed.MethodsOR or risk ratio (RR) from each study was obtained and combined for evaluating the risk. Six cohort studies and three case-control studies were included in the present study.ResultsThe meta-analysis of the highly heterogeneous case-control studies did not find significant association between maternal diabetes and ADHD risk (OR: 1.20, 95% CI: 0.96–1.49). The combining of the cohort studies demonstrated that offspring of diabetic mothers were at higher risk of ADHD (RR: 1.40, 95% CI: 1.27–1.54); however, publication bias was identified. When exposure was specified as gestational diabetes mellitus (GDM), GDM exposure increased the risk of ADHD for children by 164% (95% CI: 1.25–5.56) in a Caucasian population. Neither heterogeneity nor publication bias was detected.ConclusionMaternal diabetes, especially GDM, is probably a risk factor for ADHD in the Caucasian population. More studies based on large sample size and different ethnicities are needed to confirm this association.

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