High Sensitivity and Wide Linear Range Flexible Piezoresistive Pressure Sensor with Microspheres as Spacers for Pronunciation Recognition.

Flexible piezoresistive pressure sensors have received great popularity in flexible electronics due to their simple structure and promising applications in health monitoring and artificial intelligence. However, the contradiction between sensitivity and detection range limits the application of the sensors in the medium-pressure regime. Here, a flexible piezoresistive pressure sensor is fabricated by combining a hierarchical spinous microstructure sensitive layer and a periodic microsphere array spacer. The sensor achieves high sensitivity (39.1 kPa-1) and outstanding linearity (0.99, R2 coefficient) in a medium-pressure regime, as well as a wide range of detection (100 Pa-160.0 kPa), high detection precision (<0.63‰ full scale), and excellent durability (>5000 cycles). The mechanism of the microsphere array spacer in improving sensitivity and detection range was revealed through finite element analysis. Furthermore, the sensors have been utilized to detect muscle and joint movements, spatial pressure distributions, and throat movements during pronouncing words. By means of a full-connect artificial neural network for machine learning, the sensor's output of different pronounced words can be precisely distinguished and classified with an overall accuracy of 96.0%. Overall, the high-performance flexible pressure sensor based on a microsphere array spacer has great potential in health monitoring, human-machine interface, and artificial intelligence of medium-pressure regime.

Neural Dynamics Underlying Cognitive Control Modulated by Reinforcement Learning of Irrelevant Stimulus-Response Associations.

Human behavioral studies have shown that reward has multifaceted (motivational, learning, and emotional) effects on cognitive control. Past studies have extensively explored the neural underpinning of the motivational effect of reward on cognitive control, but less is known on the other components. The present study investigates the learning effect of reward on cognitive control with a novel paradigm reinforcing task-irrelevant stimulus-response (S-R) associations. We manipulated the contingency of irrelevant spatial stimulus-response-reward between participants (n = 54) in an orthogonal Simon task during EEG recording. The behavioral results showed that the orthogonal Simon effect in RTs and error rates increased or reversed when performance-contingent reward always followed spatially compatible or incompatible trials. The EEG results showed that the initial incorrect activation of the lateralized readiness potential, reflecting response preparation based on irrelevant spatial S-R associations, was present in the incompatible or compatible condition when reward always followed compatible or incompatible trials. Meanwhile, the P3b amplitude also showed a similar pattern of increase or reversal depending on the contingency of irrelevant stimulus-response-reward. These findings suggest that the brain used reward-strengthened irrelevant spatially compatible or incompatible S-R associations to predict responses. Moreover, the frontocentral N2 amplitude and theta band (4-8 Hz) power showed similar reward-related increase or reversal in the conflict effect, suggesting that there was conflict when the response predicted by the reward-strengthened irrelevant S-R associations was different from the correct response. Taken together, these results suggest that reinforcement learning of irrelevant spatial S-R associations can modulate cognitive control.

Active Femtoliter Droplet Generation in Microfluidics by Confined Interface Vibration.

The precise and effective generation of micron-sized droplets is one of the most common and important issues for droplet-based microfluidics. Active droplet generation makes use of additional energy input in promoting interfacial instabilities for droplet generation. Here, we report a new technique for the active generation of femtoliter droplets in microfluidic systems using confined interfacial vibration (CIV). The CIV is formed at the orifice of a traditional inkjet nozzle first by pushing the liquid out and then pulling it back. Droplets are pinched off during the withdrawal process, and this is different from the current active droplet generation techniques, which only monodirectionally push the liquid out. Droplets with radius ranging from ca. 1 to 28 µm can be actively generated by CIV at an orifice with radius 30 µm, distinguishing from conventional active generation techniques in which the droplets are always comparable or slightly bigger than the orifice. Experimental results showed that the droplet volume can be customized by controlling the intensity of the CIV. The inherent digital nature of the inkjet technique enables easy and precise regulating of the droplet volume, making it seamlessly compatible with the digital microfluidic systems.

Stroop N450 reflects both stimulus conflict and response conflict.

N450 is described as a valid event-related potential indicator of Stroop interference, but the true specific psychological meaning of the Stroop N450 remains obscure. In the present research, we first used a Chinese character incongruent-eligible task and manipulated different types of conflict to investigate whether Stroop N450 reflects stimulus conflict, response conflict or both. The results showed that, only the N450 in the incongruent-eligible condition was more negative than that of the incongruent-ineligible and neutral conditions in the frontal-central area; simultaneously, there was a left parietal-occipital N450 that successively weakened in the incongruent-eligible, incongruent-ineligible and neutral conditions. These results indicate that Stroop N450 reflects both stimulus conflict and response conflict.

Metal composition of ambient PM2.5 influences the pulmonary function of schoolchildren: A case study of school located nearby of an electric arc furnace factory.

The present study combined air sampling with pulmonary function tests (PFTs) to determine both the extent of air pollution proximal to an electric arc furnace (EAF) and its impact on human health. The mass concentrations of particulate matter with aerodynamic diameters less than 2.5 µm (PM2.5) in exposure areas were not significantly higher than the samples taken at a control area. However, the concentrations of five metal elements, Cd, Cr, Cu, Ni, and Zn in PM2.5 were significantly higher in the exposure area than that of the control area. PFTs showed that the average forced vital capacity (FVC) of boys was decreased with decreasing distance from the EAF factory. With normalization of pulmonary function by age, height, and weight, we found that the FVC became more negative with a decrease in distance from the EAF. Lastly, regression analysis was performed to analyze the impact of the concentrations of the five metals in PM2.5 on the performance of pulmonary function. The results showed that the metals can be ranked from the highest to the lowest in terms of impact on the FVC of boys as follows: Cr, Cd, Ni, Cu, and Zn. This finding is consistent with the ranking of metal toxicity reported in the literature for a rat lung epithelial cell line. The results of this study showed that only measuring PM2.5 mass concentrations may not provide a full explanation of its toxicity and health effects. The chemical composition of the PM2.5 can be an important factor that determined the health impact of PM2.5.