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. 2022 Aug 18;14:1427–1436. doi: 10.2147/NSS.S367400

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© 2022 Zhao et al.

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Circul and its working principle. (A) Circul and the accessory charger. (B) An example of Circul ring which uses the reflective SpO2 measuring method with embedded red and infra-red (IR) PPG. (C) Schematic diagram of the oxygen desaturation events detection and ODI calculation algorithm in the Circul.