Editors' ChoiceBioengineering

Worth more than the paper it’s written on

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Science Translational Medicine  27 Apr 2016:
Vol. 8, Issue 336, pp. 336ec67
DOI: 10.1126/scitranslmed.aaf7825

Many health diagnostic and monitoring methods make use of complex engineered devices familiar only to trained users. Although these toolkits, such as flow cytometry and ELISA systems, have enabled breakthroughs in health care, their complexity largely precludes use in point-of-care settings, as well as the resource-poor environments found in developing countries. In contrast, paper-based diagnostics are cheap and intuitive and have the potential to bring sensitive detection methods to austere environments, combat settings, and the point of care.

Güder et al. demonstrate a simple paper-based respiration rate sensor designed to replace the bulky and expensive temperature- and pressure-based tools used in the clinic today. Increased respiratory rate is correlated with illness, and can be a predictor for events such as heart attacks. To detect respiration, the team made use of common laboratory filter paper, which is composed of hydroscopic cellulose fibers that reversibly adsorb moisture. Advantageously, the adsorption of water changes the paper’s conductivity. The authors cleverly created a flexible conductivity measurement method by drawing an electrochemical cell on the paper using only a ballpoint pen loaded with graphite ink. When incorporated into a face-mask, the conductivity change caused by dry inhalation and moist exhalation was readily detected. Combining this paper mask with a microcontroller board and a tablet computer yielded a lightweight battery-powered and accurate respiratory sensor. The authors caution that the paper device could break if folded, and may not provide reliable readings below 0°C or in 100% humid, 37°C environments. The device’s 9-hour lifetime is limited only by the small 2600 mAh battery employed by the investigators. This simple, inexpensive, and easy-to-use device could replace the current standard of care and will enable routine respiration rate monitoring in low-resource settings around the world.

F. Güder et al., Paper-based electrical respiration sensor. Angew. Chem. Int. Ed. Engl. 10.1002/anie.201511805 (2016). [Abstract]

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