No abstract

Furthermore, by 2030 this number is expected to rise steadily to 23.6 million. [2] Despite such high mortality rates, most CVD, [3,4] including arteriosclerosis, [5,6] diabetes, [7][8][9][10] myocardial infarction, [11,12] coronary heart disease, [13,14] and hypertension, [15][16][17][18] can be prevented and treated through early diagnosis and long-term monitoring of physiological signaling. Conventional health systems suffer from deficiencies in wearability, wireless technology, lifespan, and stability to maintain a long-term collection of clinical-grade individual health metrics for accurate diagnosis. [19][20][21] As such, promoting the utility of Internet of Things (IoT)-enabled technology in personalized healthcare is still significantly impeded by the need for costeffective and wearing-comfort biomedical devices to continuously provide real-time patient-generated health data. Over the past several decades, significant advances in wearable pressure sensors have been observed, allowing them to noninvasively and continuously detect human physiological and pathological signals. [22][23][24][25][26][27][28][29][30][31][32][33][34][35] These biomedical metrics can then be used to evaluate cardiovascular conditions, providing a personalized health care system with better health outcomes, increased user-friendliness, greater quality, and cost-effectiveness that are essential to reducing CVD incidence and mortality. [36][37][38][39] Pulse waves are prominent component of human physiological signaling and involve abundant human-health information that can reveal individual conditions, including heart problems (such as arrhythmia), blood pressure, vascular aging, exercise, medication, and sleep status. [40][41][42][43][44][45] Although physical symptoms are often elusively observed in their early stages, they can be diagnosed through subtle pulsewave changes. Preventive action of CVDs can be taken by differentiating the variance of pulse waveforms with consideration of participants' age, gender, weight, and daily diet. [46][47][48][49] Traditional Chinese medicine (TCM) has proposed empirical approaches to analyze human physical state from pulse waves, rendering pulse wave surveillance unavoidable for TCM. [50,51] TCM is unable to continuously monitor pulse waves, limiting the accuracy of the assessment results. As such, empirical diagnostic methods may profoundly depend on the experiences of the practitioner, the emotions of the participant, and the external environment, resulting in the administration of distorted or problematic treatment. [52] Additionally, the diagnostic results among practitioners are Cardiovascular diseases remain the leading cause of death worldwide. The rapid development of flexible sensing technologies and wearable pressure sensors have attracted keen research interest and have been widely used for longterm and real-time cardiovascular status monitoring. Owing to compelling characteristics, including light weight, wearing comfort, and high sensitivity to pulse pressures, physiological pulse ...

Humans rely increasingly on sensors to address grand challenges and to improve quality of life in the era of digitalization and big data. For ubiquitous sensing, flexible sensors are developed to overcome the limitations of conventional rigid counterparts. Despite rapid advancement in bench-side research over the last decade, the market adoption of flexible sensors remains limited. To ease and to expedite their deployment, here, we identify bottlenecks hindering the maturation of flexible sensors and propose promising solutions. We first analyze challenges in achieving satisfactory sensing performance for real-world applications and then summarize issues in compatible sensor-biology interfaces, followed by brief discussions on powering and connecting sensor networks. Issues en route to commercialization and for sustainable growth of the sector are also analyzed, highlighting environmental concerns and emphasizing nontechnical issues such as business, regulatory, and ethical considerations. Additionally, we look at future intelligent flexible sensors. In proposing a comprehensive roadmap, we hope to steer research efforts towards common goals and to guide coordinated development strategies from disparate communities. Through such collaborative efforts, scientific breakthroughs can be made sooner and capitalized for the betterment of humanity.

The conformal integration of electronic systems with irregular, soft objects is essential for many emerging technologies. We report the design of van der Waals thin films consisting of staggered two-dimensional nanosheets with bond-free van der Waals interfaces. The films feature sliding and rotation degrees of freedom among the staggered nanosheets to ensure mechanical stretchability and malleability, as well as a percolating network of nanochannels to endow permeability and breathability. With an excellent mechanical match to soft biological tissues, the freestanding films can naturally adapt to local surface topographies and seamlessly merge with living organisms with highly conformal interfaces, rendering living organisms with electronic functions, including leaf-gate and skin-gate transistors. On-skin transistors allow high-fidelity monitoring and local amplification of skin potentials and electrophysiological signals.

Piezoelectric nanogenerators are becoming a compelling bioelectronics platform technology for human-associated energy harvesting, self-powered sensing, and therapeutics, which will largely contribute to the medical field in the era of the Internet of things.