Hemodynamic monitoring can reflect cardiac function and blood perfusion and is an indispensable monitoring method in clinical practice. Invasive hemodynamic monitoring methods represented by the thermodilution method are limited in their clinical application scope because they require vascular cannulation. Non-invasive hemodynamic monitoring has attracted extensive attention from medical companies and clinicians at home and abroad in recent years due to its advantages such as safety, non-invasiveness, continuous monitoring, simple operation, and low cost. This paper designs a non-invasive hemodynamic monitoring system based on the impedance cardiography, including hardware, algorithm, software design, and performance parameter evaluation. Among them, the hardware part mainly includes a differential high-frequency constant current source stimulation circuit, impedance cardiogram signal acquisition, and ECG signal acquisition circuit. Signal processing includes wave filtering, impedance cardiogram signal calibration, and ECG signal and impedance cardiogram signal feature point recognition. According to the collected impedance cardiogram and ECG signals, hemodynamic parameters such as heart rate (HR), stroke volume (SV), cardiac output (CO), stroke index (SI), cardiac index (CI), and cardiac contractility index (ICON) are calculated based on the Nyboer thoracic cylinder model. After testing, the key technical indicators of the system hardware are better than that of the relevant medical device standards. The system was used to collect impedance cardiogram and ECG signal data from 40 volunteers. The calculated HR, SV, and CO, three important hemodynamic indicators, were compared with the ICONCore non-invasive cardiac output monitor of OSYPKA Medical in Germany. Their Pearson correlation coefficients were 0.992 ( P<0.001), 0.948 ( P<0.001), and 0.933 ( P<0.001), respectively, verifying that the designed system has high accuracy and reliability.
Cardiography, Impedance/methods* ; Humans ; Hemodynamic Monitoring/methods* ; Equipment Design ; Signal Processing, Computer-Assisted ; Hemodynamics ; Algorithms ; Monitoring, Physiologic/methods* ; Electrocardiography

At present, there is no effective drug treatment for obstructive sleep apnea hypopnea syndrome (OSAHS). It is usually treated by mechanical ventilation through a ventilator. In this paper, a non-invasive bi-level breathing therapy system suitable for home scenarios is developed. The system supports single-level and bi-level positive airway pressure therapies, and introduces the function of inspiratory synchronous trigger based on flow monitoring to enhance the synchrony of patient-ventilator synchronization. The test results show that the performance indicators of the system meet expectations. Each ventilation mode can operate normally and can meet the requirements for the use of home non-invasive ventilators.
Humans ; Sleep Apnea, Obstructive/therapy* ; Equipment Design ; Noninvasive Ventilation/instrumentation* ; Respiration, Artificial

End-tidal carbon dioxide monitoring is an important means of evaluating human lung function and is widely used in fields such as clinical emergency treatment and cardiopulmonary resuscitation. This paper develops a microstream end-tidal carbon dioxide monitoring system. It adopts an integrated gas circuit design to further reduce the size of the equipment. The system uses the method of calculating the root mean square (RMS) of differential pressure signals to regulate the gas circuit flow, enabling the system to stably operate at a flow state of 30 mL/min. In addition, by simultaneously detecting multiple environmental parameters such as temperature and pressure, the system realizes system state monitoring and gas parameter compensation. The test results show that various indicators of the system meet the requirements of relevant standards, laying a good foundation for subsequent engineering applications.
Carbon Dioxide/analysis* ; Equipment Design ; Monitoring, Physiologic/methods* ; Humans

In order to improve the effect of transcranial electrical stimulation treatment and realize personalized treatment for patients with varying severity levels, this paper designed an integrated four-channel EEG recording multimodal transcranial electrical stimulation system. This system can conduct real-time monitoring on EEG and related characteristic analysis before stimulation, in stimulation, and after stimulation. This enables physicians and researchers to resolve real-time brain states, evaluate transcranial electrical stimulation effect, and then artificially adjust the stimulation parameters. After relevant testing and verification, the system can select four stimulation modes: TACS, TDCS, TPCS and TRNS, which can output the constant stimulation current of 0.03 mA accuracy in the range of ±2 mA and the stimulation frequency of low frequency of 0~4 kHz (precision of 0.01 Hz) and high frequency 50~100 kHz, which can obtain more accurate EEG signals under stimulation interference, demonstrating a good market application prospect.
Electroencephalography/methods* ; Transcranial Direct Current Stimulation/instrumentation* ; Humans ; Equipment Design

This paper introduces a 16-channel multimodal high-precision transcranial electrical stimulation system specifically for non-invasive brain stimulation. This system added TMCS mixed four traditional stimulation modes with TACS, TDCS, TPCS and TRNS. By designing a compensated high-precision constant current source, the constant stimulation current with an accuracy of 0.03 mA in the range of ±2 mA and the stimulation frequency of 50~200 kHz with low frequency of 0~4 kHz (high frequency of 0.1 Hz) are realized. In TACS stimulation mode, there are five adjustable wave forms: triangular wave, sine wave, sawtooth wave, square wave and mixed wave. The system has dual closed-loop control overcurrent detection and simultaneous real-time electrode contact impedance detection. After relevant tests and verification, the system has good stimulation accuracy, high safety and reliability. Compared with the existing products at home and abroad, it features lower cost, richer stimulation mode and waveforms, demonstrating a certain market application value.
Transcranial Direct Current Stimulation/instrumentation* ; Equipment Design ; Humans

Cardiovascular disease (CVD) is the leading cause of death worldwide. As the key pathological basis of CVD, arteriosclerosis holds great significance for early screening. However, existing clinical and homecare detection devices have many shortcomings; for instance, the commonly used non-invasive indicator PWV (pulse wave velocity) is easily interfered by blood pressure.This study developed a homecare arteriosclerosis monitoring system, which integrates the measurement functions of cardio-ankle vascular index (CAVI) and ankle-brachial index (ABI). The hardware design of the system includes an integrated structure of flexible silver ion electrodes and clip-type cuffs, a contact heart sound sensor, and a stepped deflation blood pressure measurement module. Meanwhile, a high-precision analog-to-digital conversion module and the STM32F405 main control chip are used to realize the synchronous acquisition of multiple signals.In terms of software, the underlying driver program was designed through MDK (Keil5), and a user interface was built on the Visual Studio platform to achieve functions such as data acquisition, display, and storage. At the algorithm level, the system adopted algorithms like the Pan-Tompkins algorithm to identify key feature points of physiological signals, and then calculate CAVI and ABI.System test results show that the ECG input noise of the system is less than 20 μV, the common-mode rejection ratio is 95 dB, and the blood pressure measurement error does not exceed 2 mmHg, which meets the design goals. Clinical data analysis indicates that CAVI is highly positively correlated with pulse wave velocity (PWV) ( r=0.85, P<0.001), but CAVI is less affected by blood pressure fluctuations. In addition, with the increase of risk factors (such as hypertension, hyperlipidemia, coronary heart disease, etc.) and age, arteriosclerosis indicators (CAVI, PWV, ABI) all show an upward trend.In conclusion, the homecare arteriosclerosis monitoring system proposed in this study not only overcomes the problems of traditional devices that rely on professional operation and are susceptible to blood pressure interference, but also provides a reliable tool for arteriosclerosis screening in home scenarios, and has important reference value for clinical diagnosis.
Humans ; Cardio Ankle Vascular Index ; Home Care Services ; Atherosclerosis/diagnosis* ; Ankle Brachial Index ; Algorithms ; Pulse Wave Analysis ; Arteriosclerosis/diagnosis* ; Monitoring, Physiologic/instrumentation*

In the past 20 years,near infrared spectrum technology has been widely used in human body monitoring due to its non-invasive and real-time characteristics.Oxygen,as the main metabolic substance of the human body,is consumed the most in brain tissue.In order to prevent complications caused by a decrease in brain tissue oxygen during treatment,the patient's brain tissue blood oxygen saturation needs to be monitored in real time.Currently,most of the clinically used non-invasive cerebral blood oxygen detection equipments use dual wavelengths.Other substances on the detection path will cause errors in the measurement results.Therefore,this article proposes a three-wavelength method based on the basic principle of non-invasive monitoring of cerebral blood oxygen using near-infrared spectrum.The brain tissue oxygen saturation monitoring method of detecting light sources was initially verified through the built system,laying the foundation for subsequent system engineering.

A wireless wearable sleep monitoring system based on EEG signals is developed.The collected EEG signals are wirelessly sent to the PC or mobile phone Bluetooth APP for real-time display.The system is small in size,low in power consumption,and light in weight.It can be worn on the patient's forehead and is comfortable.It can be applied to home sleep monitoring scenarios and has good application value.The key performance indicators of the system are compared with the industry-related medical device measurement standards,and the measurement results are better than the special standards.

The concentration of end-tidal carbon dioxide is one of the important indicators for evaluating whether the human respiratory system is normal.Accurately detecting of end-tidal carbon dioxide is of great significance in clinical practice.With the continuous promotion of the localization of end-tidal carbon dioxide monitoring technology,its application in clinical practice in China has become increasingly widespread in recent years.The study is based on the non-dispersive infrared method and comprehensively elaborates on the detection principle,gas sampling methods,key technologies,and technological progress of end-tidal carbon dioxide detection technology.It comprehensively introduces the current development status of this technology and provides reference for application promotion and further improvement.

Pulse rate and blood oxygen levels are crucial physiological parameters that reflect physiological and pathological information within the human body.The system designs a wireless pulse wave monitoring system utilizing a flexible reflective probe and the AFE4490,which is capable of monitoring pulse wave and blood oxygen levels on the human forehead.The system is predominantly based on a reflective flexible probe,the AFE4490,a power supply module,a control microcontroller unit(MCU),and a Wi-Fi module.Post-processing by a slave computer,the collected pulse wave data is wirelessly transmitted to a smartphone.The real-time pulse waveform,pulse rate,and blood oxygen levels are displayed on an application.Following relevant tests and verifications,the system can accurately detect pulse wave signals,meet the requirements for wearable technology,and possesses significant market application potential.