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. 2023 Feb 24;1(5):346–360. doi: 10.1038/s44222-023-00032-w

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© Springer Nature Limited 2023, Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

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Fig. 2 — a, Portable blood glucose meter consisting of a handheld electrochemical detector and disposable test strips. The test strip contains a bottom electrode layer, an adhesive spacer layer and a hydrophilic cover layer. The blood sample is introduced to the reaction chamber by capillary force. b, A paper-based microfluidic electrochemical biosensor for the detection of adenosine through aptamer-based affinity sensing. In one channel, adenosine is recognized by aptamer-functionalized microbeads (blue), resulting in the release of glucose oxidase-labelled DNA to catalyze the oxidation of glucose, which leads to the conversion of [Fe(CN)₆]³⁻ to [Fe(CN)₆]⁴⁻. In the other channel, the microbeads are not functionalized (purple), allowing quantification of adenosine concentration. The current signal from the discharging of the capacitor is collected by a portable digital multimeter. ox, oxidation; red, reduction. Part b reprinted with permission from ref. ¹⁰⁴, Wiley.