Ultrasensitive Fingertip-Contacted Pressure Sensors To Enable Continuous Measurement of Epidermal Pulse Waves on Ubiquitous Object Surfaces

The fingertip-pulse waveform carries abundant information regarding human physiological condition that is fundamental for directly extracting physiological parameters. Making the surfaces of ordinary objects that are often in contact with fingertips, such as tables and computers, capable of perceiving dynamic epidermal pulse signals has great significance for accurately assessing health conditions without restrictions on time and place. Here, we demonstrate the materials and design of a nanohemispherical pressure sensor that can be attached to ubiquitous objects' surfaces to monitor fingertip pulse. The portable sensor achieved an ultrasensitivity of 49.8 mV/Pa, a prominent response time of less than 6 ms, and long-term durability of more than 4 months. As demonstrated, the sensor is utilized to measure subtle fingertip-pulse waves and extract characteristic points of the waveform on the surface of keyboards, mobile phones, and human skin. Given the superior performance of the sensor, a real-time, wireless arteriosclerosis monitoring system is developed. By analyzing the characteristic parameters of the pulse waveforms measured from 54 volunteer participants, the antidiastole of arteriosclerosis could be instructively diagnosed. The sensor proposed in this work is expected to be a competitive alternative to current complicated medical equipment and to be extensively applied in wireless cardiovascular monitoring systems.

SIMULATION ANALYSIS OF BLOOD FLOW IN ARTERIES OF THE HUMAN ARM

Arteries in the upper limb play important roles in the circulation system of the human body. In particular, the radial artery has received considerable attention in traditional Chinese medicine for thousands of years. Here, a 3D model for the arm arteries has been created uncomplicated, in a Chinese adult's left hand, from the magnetic resonance imaging data, using professional modeling software to restore the basic structure of the arm artery in human body, before being imported to Ansys software for simulation. Blood model has been only simulated, and using the blood density of constant parameter and viscosity using the Carreau fluid model, and using viscous-laminar model of Fluent to obtain the velocity profile, static pressure and shear stress in the brachial, interosseous, ulnar, radial and palmar arch arteries. In particular, the brachial and bifurcations have the high pressure and velocity profiles. The simulation results obtained here are also validated by those published in the literature and proved the ulnar artery prevails over the radial artery as a blood supplier to the vessels in the wrist and hand.

A Wearable and Highly Sensitive Graphene Strain Sensor for Precise Home-Based Pulse Wave Monitoring

Profuse medical information about cardiovascular properties can be gathered from pulse waveforms. Therefore, it is desirable to design a smart pulse monitoring device to achieve noninvasive and real-time acquisition of cardiovascular parameters. The majority of current pulse sensors are usually bulky or insufficient in sensitivity. In this work, a graphene-based skin-like sensor is explored for pulse wave sensing with features of easy use and wearing comfort. Moreover, the adjustment of the substrate stiffness and interfacial bonding accomplish the optimal balance between sensor linearity and signal sensitivity, as well as measurement of the beat-to-beat radial arterial pulse. Compared with the existing bulky and nonportable clinical instruments, this highly sensitive and soft sensing patch not only provides primary sensor interface to human skin, but also can objectively and accurately detect the subtle pulse signal variations in a real-time fashion, such as pulse waveforms with different ages, pre- and post-exercise, thus presenting a promising solution to home-based pulse monitoring.