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The flexible pressure sensor is the foundation of wearable / implantable biosensing and human-machine interface, which mainly consists of the piezoresistive, capacitive, piezoelectric, and triboelectric types. As each type of...

Flexible piezoresistive sensors, which attract considerable research interest, have been extensively investigated by many efforts from material and structural methodologies. However, practical applications for physiological assessment, apart from the monitoring of joint motion and recording of pulse, have been rarely reported. In this work, vertical graphene (VG) nanowalls were synthesized, characterized, and adopted to fabricate flexible strain sensors. Routine measurements, such as strain responsion, were exerted. Then, the radial and carotid pulses and the respiratory rate of subjects were collected by these flexible piezoresistive sensors to evaluate the pulse rate, the rhythm of pulse, and the respiratory rate for risk assessment of cardiac bradycardia, arrhythmias, arrest, and artery stiffening. Furthermore, a wearable circuit was also designed and fabricated in this work to integrate with the flexible sensor for portable physiological monitoring. The convenient noninvasive platform makes it extremely suitable for wide applications at community levels, which help to raise and sustain awareness of the importance of vital signs.

The microneedle-extraction system integrated with patterned electrodes can provide convenient, mininally invasive detection of bio-analytes, including glucose, pH and H2O2.

Tongue is a unique organ that senses tastes, and the scientific puzzle about whether electricity can evoke taste sensations and how the sensations have been distributed on the tongue has not been solved. Investigations on tongue stimulation by electricity might benefit the developments of techniques for clinical neuromodulation, tissue activation, and a brain–tongue–machine interface. To solve the scientific puzzle of whether electrical stimulation induces taste-related sensations, a portable flexible tongue electrode array system (FTEAS) was developed, which can synchronously provide electrical stimulation and signal mapping at each zone of the tongue. Utilizing the FTEAS to perform tests on the rat tongue in vivo, specific electrical signals were observed to be evoked by chemical and electrical stimulations. The features and distributions of the electric signals evoked during the rat tongue tests were systematically studied and comprehensively analyzed. The results show that an appropriate electrical stimulation can induce multiple sensations simultaneously, while the distribution of each sensation was not significantly distinguished among different zones of the tongue, and at the same time, this taste-related electrical signal can be recorded by the FTEAS. This work establishes a promising platform to solve the scientific puzzle of how sensations are activated chemically and electrically on the tongue and may provide advanced noninvasive oral-electrotherapy and a brain–tongue–machine interface.