Highlights Summarizes photoacoustic imaging for monitoring of stroke diseases. Focuses on the potential photoacoustic systems for human monitoring. Reports the challenges of stroke monitoring in the human brain.

A dispersive delay structure, or phaser, is an integral part of analogue signal processor. A phaser is a circuit, whose group delay can be engineered to obtain the desired response as a function of frequency. Traditionally, phasers have been implemented in circuits or waveguide structures, but they can never deal with electromagnetic waves in free space due to limitation of natural materials. To resolve this drawback, a novel metasurface‐based structure, spatial phaser, for analogue signal processing in the spatial domain is proposed. A general design theory is put forward to realize the spatial phaser for manipulating the dispersive delay of electromagnetic waves. To demonstrate this method, three spatial phasers with different group‐delay responses are elaborately devised and a prototype that exhibits a positive‐triangular group delay from 8 to 10 GHz is fabricated. The experimental and simulation results show good agreement. This work will facilitate the development of real‐time analogue signal processing in spatial domain for applications in radars, electronic countermeasures, and other related areas.

Obstructive sleep apnea (OSA), a common sleep disorder disease, affects millions of people. Without appropriate treatment, this disease can provoke several health-related risks including stroke and sudden death. A variety of treatments have been introduced to relieve OSA. The main present clinical treatments and undertaken research activities to improve the success rate of OSA were covered in this paper. Additionally, guidelines on choosing a suitable treatment based on scientific evidence and objective comparison were provided. This review paper specifically elaborated the clinically offered managements as well as the research activities to better treat OSA. We analyzed the methodology of each diagnostic and treatment method, the success rate, and the economic burden on the world. This review paper provided an evidence-based comparison of each treatment to guide patients and physicians, but there are some limitations that would affect the comparison result. Future research should consider the consistent follow-up period and a sufficient number of samples. With the development of implantable medical devices, hypoglossal nerve stimulation systems will be designed to be smart and miniature and one of the potential upcoming research topics. The transcutaneous electrical stimulation as a non-invasive potential treatment would be further investigated in a clinical setting. Meanwhile, no treatment can cure OSA due to the complicated etiology. To maximize the treatment success of OSA, a multidisciplinary and integrated management would be considered in the future.

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