Smart Mask as Wearable for Post-Pandemic Personal Healthcare

Abstract

A mask serves as a simple external barrier that protects humans from infectious particles from poor air conditions in the surrounding environment. As an important personal protective equipment (PPE) to protect our respiratory system, masks are able not only to filter pathogens and dust particles but also to sense, reflect or even respond to environmental conditions. This smartness is of particular interest among academia and industries due to its potential in disease detection, health monitoring and caring aspects. In this review, we provide an overlook of the current air filtration strategies used in masks, from structural designs to integrated functional modules that empower the mask's ability to sense and transfer physiological or environmental information to become smart. Specifically, we discussed recent developments in masks designed to detect macroscopic physiological signals from the wearer and mask-based disease diagnoses, such as COVID-19. Further, we propose the concept of next-generation smart masks and the requirements from material selection and function design perspectives that enable masks to interact and play crucial roles in health-caring wearables.

Keywords: intelligent materials; respirator; sensor; smart wearables; sustainability.

Figure 1

Mask filters out pathogens from the environment and provides wearers with quality air.

Figure 2

Filtration performance and functionalities of the mask rely on its structural designs: (a) Dynamic adjustment of micropore sizes of an elastic nanofiber-based air filter (Adapted and reproduced with permission from Ref. [29]. Copyright 2021, American Chemical Society); (b) A self-powered pressure sensor on mask for breath detection enabled by electrostatic induction effect (Reproduced with permission from Ref. [30]. Copyright 2022, Wiley-VCH GmbH, Weinheim); (c) Fibrous membrane for air filtration with a hierarchical structure (Adapted and reproduced with permission from Ref. [31]. Copyright 2018, Elsevier B.V.); (d) Particulate matter capture mechanisms: electrostatic attraction, diffusion, interception and impaction (Adapted and reproduced with permission from Ref. [23]. Copyright 2021, Elsevier B.V.); (e) Printed electrodes on mask as biosensor that detects glucose level continuously (Adapted and reproduced with permission from Ref. [32]. Copyright 2022, Elsevier B.V.).

Figure 3

Mask filtration material development: a trend to higher porosity and improved filtration efficiency.

Figure 4

Nanofibrous mat prepared by electrospinning for filtration: (a) Filtration works with physical sieving (Adapted and reproduced with permission from Ref. [65]. Copyright 2017, Springer Nature); (b) Electrospun air filters have eminently better performance than commercial face masks (Reprinted with permission from Ref. [96]. Copyright 2017, American Chemical Society); (c) Secondary structure of helical wrinkled nanofibers introduced by electrospinning (Reproduced with permission from Ref. [66]. Copyright 2022, Elsevier B.V.); (d) Self-powered facemask based on electrospun triboelectric nanogenerator (Adapted and reproduced with permission from Ref. [35]. Copyright 2018, American Chemical Society).

Figure 5

Mask detects macroscopic physiological signals: (a) A smart mask integrated with a sensor system that can remotely monitor variables like respiratory rate, heart rate, skin temperature and blood oxygen saturation (Reproduced with permission from Ref. [105]. Copyright 2020, American Chemical Society); (b) A self-powered mask with a sensor that detects coughs and wearing by mask deformation (Adapted and reproduced with permission from Ref. [136]. Copyright 2022, American Chemical Society); (c) A smart mask with CO₂ sensitive membrane that wirelessly detects CO₂ level around the wearer (Adapted and reproduced with permission from Ref. [137]. Copyright 2022, Springer Nature); (d) A cellulose paper-based mask that functions as a moisture sensor (Reprinted with permission from Ref. [138]. Copyright 2016, Wiley-VCH GmbH, Weinheim).

Figure 6

Mask-based COVID-19 diagnosis: (a) A face-mask-integrated sensor for SARS-CoV-2 detection in exhaled aerosols (Adapted and reproduced with permission from Ref. [140]. Copyright 2021, Springer Nature); (b) A mask-based diagnostic platform for point-of-care screening of COVID-19 (Reprinted with permission from Ref. [141]. Copyright 2021, Elsevier B.V.); (c) An intelligent face mask integrated with a high-density conductive nanowire array for directly exhaled coronavirus aerosol screening (Reprinted with permission from Ref. [142]. Copyright 2021, Elsevier B.V.).