Search

Carbon monoxide (CO) gas sensors are widely used, especially for environmental monitoring in confined spaces such as the landscape of mining cave ruins in mining parks, which is essential for ensuring the health and safety of tourists and staff. In this paper, a flexible CO gas sensor based on polyimide, interdigital electrodes, and reduced graphene oxide (RGO)/cuprous chloride (CuCl) composite film is designed and manufactured for reliable room temperature detection of high-concentration CO gas. The structure size of RGO/CuCl gas-sensitive film is 5 × 5 mm. The RGO with a 62.65% C-C bond is prepared by the thermal reduction method. The test results show that the sensor has a high response in the range of 400–2000 ppm CO gas concentration, and the maximum response is 1.56. The linear correlation coefficient of the sensor is 0.981, which indicates that the sensor has good output response characteristics. The response time of the sensor for 400 ppm CO gas is 332 s, which indicates that the sensor has a fast response rate. Furthermore, compared with other gases, the sensor shows higher gas selectivity for CO gas. This sensor has the characteristics of small size and easy attachment; therefore, it can be installed on the shoulder or helmet of tourists’ safety suits, providing personalized real-time warning prompts for tourists’ physical health status.

Abstract With the rapid development and application of smart homes, sensors known as ‘neurons’ have become more and more important in this field. In response to the demand for relative humidity parameter in home monitoring, a flexible relative humidity sensor based on reduced graphene oxide (RGO) and interdigital electrode for smart homes was designed and prepared in this paper. The base of the interdigital electrode structure was polyimide, and the RGO film was prepared by a spraying process. A test system for the relative humidity sensor with different saturated salt solutions was also built. The test results show that the sensor resistance and relative humidity have a linear relationship in the range of 24.6% RH–82.9% RH, and the linearity is as high as 0.987. The sensitivity of the sensor is 0.51 kΩ/% RH. The relative humidity sensor with the characteristics of flexibility and high sensitivity will have broad application prospects and value in the field of smart homes.

Abstract Flexible sensors used to detect NO2 gas generally have problems such as poor repeatability, high operating temperature, poor selectivity, and small detection range. In this work, a new spraying platform with a simple structure, low cost, and good film-forming consistency was designed and built to make a sensitive film (rGO/SnO2) for NO2 gas sensors. The relationship between the solid content of rGO and SnO2 nanoparticles, annealing temperature, and sensor performance was studied. The results show that the interdigital electrode-sensitive film formed by spraying 0.25 ml of a 0.4 wt% rGO/SnO2 mixture and annealing at 250 °C exhibited the best comprehensive performance for NO2 detection. The sensor’s response value for 100 ppm NO2 gas was 0.2640 at room temperature (25 °C), and the response time and recovery time were 412.4 s and 587.3 s, respectively. In the range of 20–100 ppm, the relationship between the response and NO2 concentration was linear, and the correlation coefficient was 0.9851. In addition, a soft-monitoring node module with an overlimit warning function for NO2 gas was designed and manufactured based on flexible electronics. Finally, the flexible sensor and node module were embedded into woven fabric that could be used to make a mask or a watch that could detect NO2 gas, realizing the practical application of flexible NO2 gas sensors in the field of wearable electronics.

At present, flexible pressure-sensitive materials generally have problems with weak adhesion and poor wear resistance, which easily result in friction failure when used for plantar pressure detection. In this study, a flexible pressure sensor with the advantages of a wide detection range, fast recovery, and good abrasive resistance was designed and prepared based on the screen printing process. The pressure-sensitive unit with a structural size of 5 mm× 8 mm was a functional material system due to the use of graphene and epoxy resin. The influence of the different mass ratios of the graphene and epoxy resin on the sensing properties was also studied. The test results showed that when the mass ratio of graphene to epoxy resin was 1:4, the response time and recovery time of the sensing unit were 40.8 ms and 3.7 ms, respectively, and the pressure detection range was 2.5–500 kPa. The sensor can detect dynamic pressure at 0.5 Hz, 1 Hz, 2 Hz, 10 Hz, and 20 Hz and can withstand 11,000 cycles of bending. In addition, adhesion tests showed that the high viscosity of the epoxy helped to improve the interlayer bond between the pressure-sensitive materials and the flexible substrate, which makes it more suitable for plantar pressure detection environments, where friction is common.

Here, we present a high-precision demodulation method that supports the arrayed waveguide grating (AWG) system, which includes a 1 × 8 AWG as the primary filter with a 0.5 nm channel spacing and a 1 × 4 AWG as the auxiliary filter with a 1 nm channel spacing. The high precision is achieved through an innovative method of decoupling three channels, involving two adjacent channels of the primary filter and one channel of the secondary auxiliary filter. Simulation results show that the AWGs have a good transmission spectrum with crosstalk below −24.8 dB, non-uniformities below 0.8 dB, insertion loss below −3.7 dB, 3 dB bandwidth of 0.25 nm, and 10 dB bandwidth of 0.43 nm. The interrogation precision can reach 8 pm, with a dynamic range of 0.4 nm, corresponding to a single FBG.

Abstract Background Despite the capability of emergency surgery to reduce the mortality of severe spontaneous intracranial hemorrhage (SSICH) patients, the effect and safety of surgical treatment for severe spontaneous intracranial hemorrhage (SSICH) patients receiving long-term oral antiplatelet treatment (LOAPT) remains unclear. In consideration of this, the cohort study is aimed at figuring out the effect and safety of emergency surgery for SSICH patients on LOAPT. Methods As a multicenter and prospective cohort study, it will be conducted across 7 representative clinical centers. Starting in September 2019, the observation is scheduled to be completed by December 2022, with a total of 450 SSICH patients recruited. The information on clinical, radiological, and laboratory practices will be recorded objectively. All of the patients will be monitored until death or 6 months after the occurrence of primary hemorrhage. Results In this study, two comparative cohorts and an observational cohort will be set up. The primary outcome is the effect of emergency surgery, which is subject to assessment using the total mortality and comparison in the survival rate of SSICH patients on LOAPT between surgical treatment and conservative treatment. The second outcome is the safety of surgery, with the postoperative hemorrhagic complication which is compared between the operated SSICH patients on and not on LOAPT. Based on the observation of the characteristics and outcome of SSICH patients on LOAPT, the ischemic events after discontinuing LOAPT will be further addressed, and the coagulation function assessment system for operated SSICH patients on LOAPT will be established. Conclusions In this study, we will investigate the effect and safety of emergency surgery for SSICH patients on LOAPT, which will provide an evidence for management in the future. Ethics and dissemination The research protocol and informed consent in this study were approved by the Institutional Review Board of Beijing Tiantan Hospital (KY2019-096-02). The results of this study are expected to be disseminated in peer-reviewed journals in 2023. Trial registration Name: Effect and safety of surgical intervention for severe spontaneous intracerebral hemorrhage patients on long-term oral antiplatelet treatment. ChiCTR1900024406 . Date of registration is July 10, 2019.

GaN high-electron-mobility transistor (HEMT) terahertz (THz) detectors have been widely studied and applied in the past few decades. However, there are few reports about the influence of GaN/AlGaN heterostructure material properties on the detection model at present. In this paper, a response voltage model for a GaN HEMT THz detector that considers the carrier scattering in a GaN/AlGaN heterostructure is proposed. The phonon scattering, dislocation scattering, and interface roughness scattering mechanisms are taken into account in the classic THz response voltage model; furthermore, the influence of various material parameters on the response voltage is studied. In a low-temperature region, acoustic scattering plays an important role, and the response voltage drops with an increase in temperature. In a high temperature range, optical phonon scattering is the main scattering mechanism, and the detector operates in a non-resonant detection mode. With an increase in carrier surface density, the response voltage decreases and then increases due to piezoelectric scattering and optical phonon scattering. For dislocation and interface roughness scattering, the response voltage is inversely proportional to the dislocation density and root mean square roughness (RMS) but is positively related to lateral correlation length. Finally, a comparison between our model and the reported models shows that our proposed model is more accurate.

Abstract Background This study aimed to compare the efficacy and toxicity of raltitrexed (Saiweijian®) plus cisplatin (SP regimen) and 5‐fluorouracil plus cisplatin (FP regimen) as concurrent chemoradiotherapy (CCRT) in patients with locally advanced nasopharyngeal carcinoma (LA‐NPC). Methods Eligible patients (N = 135) were allocated randomly in a ratio of 1:1 to receive CCRT with either SP or FP. At least 2 cycles of chemotherapy was administrated during radiotherapy. Progression free survival (PFS) was primary endpoint. Secondary endpoints included overall survival (OS), loco‐regional relapse free survival (LRRFS), distant metastasis free survival (DMFS) and toxicity. Results In this study, 68 patients received SP as CCRT, and 67 received FP. Objective responses were noted in 97.1% of the patients in the SP group and in 97.0% of the patients in the FP group (P = 1.00). At the end of a median 36 months follow‐up period, the estimated 3‐year PFS rates were 70.1% for SP and 66.6% for FP, respectively. The 3‐year LRRFS, DMFS and OS rates were 88.9%, 74.7% and 84.0%, respectively, for the SP group, and 92.3%, 71.0% and 73.7%, respectively, for the FP group. Overall, there was no difference between treatment groups with regard to response or survival. The most frequent acute toxicities monitored in both groups were bone marrow suppression, gastrointestinal side effects and oral mucositis (OM). The overall incidence of grade 3‐4 OM in the FP group (47.8%) was higher than in the SP group (11.8%). However, the incidence of other adverse effects observed in both groups was similar (P > .05). Conclusions These data indicate that SP and FP therapies have similar efficacy in treating LA‐NPC. The SP regimen showed a tolerable safety profile along with a lower frequency of severe OM and therefore, an improved life quality. In conclusion, SP was a well tolerated, effective, regimen for LA‐NPC treatment.

ZigBee technology with the characteristics of low complexity, ad- hoc network, low cost, low power consumption and high security, is widely used for wireless sensing. Wireless sensor network is an interdisciplinary application between multi-sensor technology and wireless network, and has the broad application prospects in many fields such as intelligent agriculture and smart home. This paper designs and realizes an indoor environment monitoring system based on ZigBee and wireless sensor network. The system uses end-nodes to collect temperature, humidity, PM2.5 and other environmental parameters. The collected data is transmitted to the coordinator through wireless sensor network and finally to the monitoring system software by serial port protocol. The online monitoring platform with functions of real- time data display, storage and over-limit warning is developed by using the LabVIEW software. The test results show that the system is stable, easy to generate a network system, speedy and reliable to transmit data, and flexible to place nodes.

Reduced graphene oxide (rGO) fiber as a carbon-based fiber sensor has aroused widespread interest in the field of gas sensing. However, the low response value and poor flexibility of the rGO fiber sensor severely limit its application in the field of flexible wearable electronics. In this paper, a flexible and wearable nylon fiber sensor modified by rGO and ZnO quantum dots (QDs) is proposed for wide-range NO2 gas detection at room temperature. The response value of the nylon fiber sensor to 100 ppm NO2 gas is as high as 0.4958, and the response time and recovery time are 216.2 s and 667.9 s, respectively. The relationship between the sensor’s response value and the NO2 concentration value is linear in the range of 20–100 ppm, and the fitting coefficient is 0.998. In addition, the test results show that the sensor also has good repeatability, flexibility, and selectivity. Moreover, an early warning module was also designed and is proposed in this paper to realize the over-limit monitoring of NO2 gas, and the flexible sensor was embedded in a mask, demonstrating its great application potential and value in the field of wearable electronics.

A Mach–Zehnder fiber optic sensor with high refractive index response sensitivity was developed. By fabricating a waist-enlarged bitaper structure on the interference arm of a single mode–multimode–single mode (SMS) Mach–Zehnder interferometer (MZI), the spectral contrast and response sensitivity were improved. Subsequently, the response sensitivity was further improved by etching the interference arm. When a beam of light was introduced into the sensor, due to the structural mismatch between the multimode fiber and the normal transmission light, the difference between the low-order mode and the high-order mode was generated in the fiber core and the fiber cladding. In the process of transmission in the sensing arm, due to the different refractive indices of the core and cladding, the optical path difference of the high-order mode and the low-order mode was different, which eventually generated interference fringes. The experimentally measured response sensitivity of SMS MZI in the range of 1.351 RIU to 1.402 RIU is 57.623 nm/RIU; the response sensitivity of a single mode–multimode–bitaper–multimode–single mode (SMBMS) MZI is 61.607 nm/RIU; and the response sensitivity of the etched SMBMS (ESMBMS) MZI is 287.65 nm/RIU. The response sensitivity of the new ESMBMS MZI is three times higher than that of the original SMS MZI. The sensor has the characteristics of compact structure, high sensitivity, easy manufacture, and a wide range of refractive index measurements, and can be used in food processing, pharmaceutical manufacturing and other fields.

Two sandwiched ZnO/Metal/ZnO transparent conductive thin films, 50nm ZnO/Cu/50nm ZnO (abbreviated as ZnO(Cu)) and 50nm ZnO/Ti/Cu/Ti/50nm ZnO (abbreviated as ZnO(Ti/Cu)) were deposited by magnetron sputtering technology. The comparative analysis of experiment results shows that the introduction of the Ti layer is beneficial to the overall properties of ZnO(Ti/Cu) thin film compared to ZnO(Cu) thin film with the same metal layer thickness. The effect of the annealing temperature on the performance of the two film systems was studied. Although the carrier concentration did not always increase with annealing temperature, the sheet resistances did decrease due to the obvious increase of mobility. The transmittance of ZnO(Cu) thin films increases with annealing temperature, while that of ZnO(Ti/Cu) films increases at first and then decreases. The optical band gap of ZnO(Cu) thin films increases with temperature, but is lower than that of ZnO(Ti/Cu) thin films, whose bandgap first increases with temperature and then decreases. The figure of merit of the ZnO(Ti/Cu) film is better than that of ZnO(Cu), which shows that the overall performance of ZnO(Ti/Cu) films is better, and annealing can improve the performance of the film systems.

Extrinsic optical fiber Fabry–Perot (F–P) high temperature sensors using Al2O3 ceramic tubes were fabricated by a microscope equipped with a CCD whose scaleplate has been calibrated using a standard gauge block. The initial cavity length of the F–P sensor, which must be larger than 36 µm, whose output signal is demodulated by the multi-peak method is determined. The temperature measurement range of the sensor is 25 °C–1000 °C. Because the temperature sensitivity of the F–P temperature sensor made by Al2O3 ceramic tubes, whose thermal expansion coefficient is different from that of the fiber, is dependent on the initial cavity length, a low initial cavity length is beneficial in improving sensor sensitivity. Compared with the results of the quartz tube F–P sensor, the temperature sensitivity of the ceramic tube F–P sensor is 10 times larger than that of the quartz tube F–P sensor. Hence, it can be deduced that the ceramic tube F–P sensor is greatly improved compared with the quartz tube F–P sensor.

Background: Persistent primitive hypoglossal artery (PPHA) is a rare remnant of the congenital carotid-basilar artery anastomosis, sometimes associated with subarachnoid hemorrhage (SAH), and aneurysms are the more common cause. However, the association of PPHA with perimesencephalic nonaneurysmal subarachnoid hemorrhage (PNSAH) is extremely rare. This report is the first to describe the occurrence of PNSAH concerning PPHA. Case description: A 53-year-old man suffered from subarachnoid hemorrhage with a sudden severe headache. An emergency brain computed tomography (CT) disclosed a perimesencephalic pattern of SAH. CT angiography (CTA) revealed a right PPHA entering the posterior fossa through the right enlarged hypoglossal canal. No source of the hemorrhage was identified in the imaging examinations, even with the performance of a 4-vessel angiography. Conclusion: We present a case of PPHA associated with PNSAH and review the literature. The main cause for the PPHA related to SAH is an aneurysm. The four vessels angiography helped rule out an aneurysm that is associated with a poorer prognosis and requires immediate active management. It is, therefore, essential for physicians to be aware of the increased incidence of aneurysms in PPHA to make the correct diagnosis. Keywords: Persistent primitive hypoglossal artery, Subarachnoid hemorrhage, Perimesencephalic nonaneurysmal subarachnoid hemorrhage, Carotid-basilar anastomoses, Intracranial aneurysm

The optical fiber temperature and refractive index sensor combined with the hollow needle structure for medical treatment can promote the standardization of traditional acupuncture techniques and improve the accuracy of body fluid analysis. A double-parameter sensor based on fiber Bragg grating (FBG) is developed in this paper. The sensor materials are selected through X-ray diffraction (XRD) analysis, and the sensor sensing principle is theoretically analyzed and simulated. Through femtosecond laser writing pure silica fiber, a high temperature resistant wavelength type FBG temperature sensor is obtained, and the FBG is corroded by hydrofluoric acid (HF) to realize a high-sensitivity intensity-type refractive index sensor. Because the light has dual characteristics of energy and wavelength, the sensor can realize simultaneous dual-parameter sensing. The light from the lead-in optical fiber is transmitted to the sensor and affected by temperature and refractive-index; then, the reflection peak is reflected back to the lead-out fiber by the FBG. The high temperature response and the refractive index response of the sensor were measured in the laboratory, and the high temperature characteristics of the sensor were verified in the accredited institute. It is demonstrated that the proposed sensor can achieve temperature sensing up to 1150 °C with the sensitivity of 0.0134 nm/°C, and refractive sensing over a refractive range of 1.333 to 1.4027 with the sensitivity of −49.044 dBm/RIU. The sensor features the advantages of two-parameter measurement, compact structure, and wide temperature range, and it exhibits great potential in acupuncture treatment.

In this paper, a novel micro-displacement sensor with double optical fiber probes is proposed and designed, which can realize the highly sensitive sensing of longitudinal or lateral micro-displacements. The optical fiber probes are made through photopolymer formulation, and the effects of reaction time and optical power on the growth length of the probe are illustrated. The relationship between light intensity and longitudinal micro-displacement is a power function in the range of 0–100 μm at room temperature with a correlation coefficient of 98.92%. For lateral micro-displacement, the sensitivity is −2.9697 dBm/μm in the range of 0–6 μm with a linear fit of 99.61%. In addition, the linear correlation coefficient decreases as the initial longitudinal distance increases, and the function of these correlation coefficients is also linear with a linearity of 96.14%. This sensor has a simple manufacturing process, low cost, high sensitivity, and fast response speed. It is suitable for harsh environments such as strong electromagnetic interference and corrosivity, and has a broad application prospect in the field of micro-displacement sensing.

Environmental monitoring plays an important role in the preventive protection of ancient buildings, although it is still in the prototype stage. In order to provide data support for the protection of ancient buildings, an environmental monitoring system with multi-sensor and multi-node for the interior and exterior of ancient buildings is designed and realized, based on ZigBee, TCP/IP, and intranet penetration technology. The new type of indoor node package box and outdoor package device are designed to meet the needs of different types of sensors. The monitoring platform is developed on the strength of the LabView so as to obtain real-time display, storage, and over-limit warning functions for local and remote monitoring data. It also proves that the monitoring system is stable and reliable by monitoring the actual ancient building with a brick (stone) structure.