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.

Distribution and expression of Pen-2 in the central nervous system of APP/PS1 double transgenic mice.

The γ-secretase complex catalyzes the final cleavage step of amyloid ß-protein precursor (APP) to generate amyloid ß (Aß) peptide, a pathogenic component of senile plaques in the brain of Alzheimer's disease (AD) patients. Recent studies have shown that presenilin enhancer-2 (Pen-2), presenilin (PS, including PS1 and PS2), nicastrin, and anterior pharynx-defective 1 are essential components of the γ-secretase. The structure and function of Pen-2 in vitro have been well defined. However, little is known about the neuroanatomical distribution and expression of Pen-2 in the central nervous system (CNS) of AD model mice. We report here, using various methods such as immunohistochemical staining and immunoblotting, that Pen-2 is widely expressed at specific neuronal cells of major areas in AD model mice, including the olfactory bulb, basal forebrain, striatum, cortex, hippocampus, amygdala, thalamus, hypothalamus, cerebellum, brainstem, and spinal cord. It is co-expressed with PS1 in specific neuronal cells in mouse brain. Pen-2 is distributed much more extensively than extracellular amyloid deposits, suggesting the importance of other factors in localized amyloid deposition. Pen-2 is localized predominantly in cell membrane and cytoplasma in adult AD mice, but only distributed at cell membrane in controls. At the early stages of postnatal development, the expression level of Pen-2 is relatively high in CNS, but declines, gradually in adult mice. The present study provides an anatomical basis for Pen-2 as a key component of γ-secretase complex in the brain of developing and adult mice, and Pen-2 might be closely related to Aß burden in aging nervous system.

An improved adaptive periodical segment matrix algorithm for ECG denoising based on singular value decomposition.

BACKGROUND: Wearable devices that monitor heart health of cardiac disease patients in real time are in great demand. OBJECTIVE: We propose an algorithm of improved segment periodical matrix construction for irregular electrocardiogram (ECG) signal denoising. METHOD: While splitting the heartbeat based on each RR interval for periodical segments matrix construction, the as-filtered ECG signal is reconstructed by the maximum singular value after a singular value decomposition. RESULTS: The results demonstrate a higher noise reduction effect with lower signal distortions of our methods compared to several singular value decomposition counterpart approaches. CONCLUSION: Our method has great potential to enhance wearable devices diagnosis accuracy by denoising the complex noises such as electromyography artifacts in real-time ECG sensing.