Volatile organic compounds (VOCs) are excreted through the skin or exhaled breath. They are end products of human metabolism, metabolism of gut microflora, and ingested or inhaled substances. VOCs can be noninvasively sampled and could be a useful marker for disease. However, medical diagnostics rarely considers the VOCs that are expelled from the body. Here, we introduce a miniature, low-cost, and battery-free electronic nose (e-nose) sensor for passively identifying chemical patterns that are excreted from the human skin or exhaled breath. The platform is composed of an array of conductive polymer filaments created with a two-layer system of multi-walled carbon nanotubes and four different, solution processable polymers. The “breathprint” signature–consisting of the resistance of each filament–can be read from the sensor using a near-field communication-enabled device, such as a smartphone. The e-nose sensor contains a system on a chip with near-field communication (NFC) functionality and a radio frequency antenna to harvest power. The sensor was tested against six common VOCs that are released from the human body.

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