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In this paper, a new microwave humidity sensor is proposed with the near-field self-injection-locked (NFSIL) technology. This sensor is composed of a humidity sensing oscillator and a frequency demodulator. The sensing oscillator is designed at 7.67 GHz using a substrate integrated waveguide (SIW) cavity with embedded air holes. It is used to generate an electric-field distribution in the air holes and in the near-field region. According to the self-injection-locked (SIL) theory, as the moist air is distributed in the sensing region, the oscillation frequency of the SIW oscillator varies corresponding to different relative humidity (RH) levels, namely a frequency-modulated signal produced by this sensing oscillator. A delay-line frequency discriminator is then treated as a demodulator to obtain the voltage outputs, which are related to their corresponding RH. The proposed humidity sensor has been experimentally demonstrated to have an effective capability for humidity detection over a RH range of 50%–90%. To the best of our knowledge, the proposed sensor is the first microwave sensor to detect RH without using a vector network analyzer.

At the beginning of 2020, the COVID-19 pandemic which started in Wuhan, Hubei, China has created an unprecedented crisis that influenced people’s lives and weakened the worldwide economy, particularly that of Southeast Asia. The outbreak of Covid-19 is not only a medical and health crisis, but also a serious challenge for economic growth, supply chain, and tourist industry in Southeast Asia. The economic growth in the ASEAN region is likely to stop and drop around 3.7% from the projected growth and only reach 1% growth in 2020. In a worse scenario, some ASEAN countries will have to face negative growth.

(1) Background: The present study measures the fear of COVID-19 among hospital healthcare workers and identifies several factors associated with increasing fear of COVID-19. (2) Methods: A cross-sectional, hospital-based survey was conducted on healthcare workforce recruited from the National Hospital of Tropical Diseases from 1 October 2021 and 20 October 2021. We selected the participants who have been directly involved in diagnosing, treating, or providing nursing care to patients with COVID-19. The primary data was collected via sending the invitation directly to the participants, utilizing structured self-completed questionnaires. The seven-item fear of COVID-19 scale was used to measure the data. The responses of 208 hospital healthcare workers were included in the final analysis. (3) Results: Total score of COVID-19 fear was 19.62 (SD = 5.22). The COVID-19 fear score of 7 items ranged from 2.38 (SD = 0.83) to 3.21 (SD = 0.96). The lowest and highest scores were the item ‘My hands become clammy when I think about Corona’ and the item ‘I am most afraid of corona’ was the highest, respectively. Linear regression of the COVID-19 fear showed that the factors positively correlated with the fear of COVID-19 among hospital healthcare workers were: being influenced by the community (p = 0.001), feeling at very high risk of COVID-19 (p = 0.03), and experiencing traumatic stress with an academic event (p = 0.042). (4) Conclusions: Although these findings merit further elaboration, these preliminary findings suggest relatively great fear of the COVID-19 pandemic among Vietnamese hospital healthcare workers and that social and personal connections are necessary for maintaining the mental wellbeing.