Swallowable fluorometric capsule for wireless triage of gastrointestinal bleeding.
Real-time detection of gastrointestinal bleeding remains a major challenge because there does not yet exist a minimally invasive technology that can both i) monitor for blood from an active hemorrhage and ii) uniquely distinguish it from blood left over from an inactive hemorrhage. Such a device would be an important tool for clinical triage. One promising solution, which we have proposed previously, is to inject a fluorescent dye into the blood stream and to use it as a distinctive marker of active bleeding by monitoring leakage into the gastrointestinal tract with a wireless fluorometer. This paper reports, for the first time to our knowledge, the development of a swallowable, wireless capsule with a built-in fluorometer capable of detecting fluorescein in blood, and intended for monitoring gastrointestinal bleeding in the stomach. The embedded, compact fluorometer uses pinholes to define a microliter sensing volume and to eliminate bulky optical components. The proof-of-concept capsule integrates optics, low-noise analog sensing electronics, a microcontroller, battery, and low power Zigbee radio, all into a cylindrical package measuring 11 mm × 27 mm and weighing 10 g. Bench-top experiments demonstrate wireless fluorometry with a limit-of-detection of 20 nM aqueous fluorescein. This device represents a major step towards a technology that would enable simple, rapid detection of active gastrointestinal bleeding, a capability that would save precious time and resources and, ultimately, reduce complications in patients.
Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford St., Cambridge, MA 02138, USA. alex.nemiroski@gmail.com.
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Nemiroski
Division of Gastroenterology, Brigham & Women's Hospital, 75 Francis Street, Boston, MA 02115, USA.
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Ryou
Division of Gastroenterology, Brigham & Women's Hospital, 75 Francis Street, Boston, MA 02115, USA.
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Thompson
John A. Paulson School of Engineering and Applied Sciences, Harvard University, 9 Oxford St., Cambridge, MA 02138, USA and Department of Physics, Harvard University, 9 Oxford St., Cambridge, MA 02138, USA. bmw@seas.harvard.edu.
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Westervelt
D000328:Adult; D002214:Capsules; D003679:Deglutition; D011211:Electric Power Supplies; D004867:Equipment Design; D019793:Fluorescein / Q000737:chemistry / Q000493:pharmacokinetics; D005470:Fluorometry / Q000295:instrumentation*; D006471:Gastrointestinal Hemorrhage / Q000175:diagnosis*; D006801:Humans; D008297:Male; D055620:Optical Phenomena; D014218:Triage / Q000379:methods*; D059015:Wireless Technology
D002214:Capsules; D019793:Fluorescein