title: Clinical chemistry measurements with commercially available test slides on a smartphone platform: Colorimetric determination of glucose and urea.
abstract: BACKGROUND
  Rapidly increasing healthcare costs in economically advantaged countries are currently unsustainable, while in many developing nations, even 50-year-old technologies are too expensive to implement. New and unconventional technologies are being explored as solutions to this problem. In this study, we examined the use of a smartphone as the detection platform for 2 well-developed, relatively inexpensive, commercially available clinical chemistry assays as a model for rapid and inexpensive clinical diagnostic testing.
  
  
  METHODS
  An Apple iPhone 4 camera phone equipped with a color analysis application (ColorAssist) was combined with Vitros® glucose and urea colorimetric assays. Color images of assay slides at various concentrations of glucose or urea were collected with the iPhone 4 and quantitated in three different spectral ranges (red/green/blue or RGB) using the ColorAssist app. When the diffuse reflectance data was converted into absorbance, it was possible to quantitate glucose or blood urea nitrogen (BUN) over their clinically important concentration ranges (30-515mg/dl for glucose or 2-190mg/dl for BUN), with good linearity (R(2)=0.9994 or 0.9996, respectively [n=5]).
  
  
  RESULTS
  Data collected using the iPhone 4 and canine serum samples were in agreement with results from the instrumental "gold standard" (Beckman Coulter AU480 Chemistry System) (R(2)=0.9966 and slope=1.0001 for glucose; R(2)=0.9958 and slope=0.9454 for BUN). Glucose determinations of serum samples made using this smartphone method were as accurate as or more accurate than a commercial colorimetric dry slide analyzer (Heska® Element DC Chemistry Analyzer, Loveland, CO) and 2 glucometers: ReliOn® Ultima (Abbott Diabetes Care Inc) and Presto® (AgaMatrix Inc.H). BUN determinations made using the smartphone approach were comparable in accuracy to the Heska instrument.
  
  
  CONCLUSIONS
  This demonstration shows that smartphones have the potential to be used as simple, effective colorimetric detectors for quantitative diagnostic tests, and may be applicable for both point-of-care applications in the developed world and field deployment in developing nations.
authors.affiliation: Department of Chemistry, Oregon State University, Corvallis, OR 97331, USA.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Department of Chemistry, Oregon State University, Corvallis, OR 97331, USA.
authors.forename: Anukul
authors.initials: A
authors.lastname: Boonloed
authors.affiliation: Department of Chemistry, Oregon State University, Corvallis, OR 97331, USA.
authors.forename: Neal
authors.initials: N
authors.lastname: Sleszynski
authors.affiliation: Department of Chemistry, Oregon State University, Corvallis, OR 97331, USA.
authors.forename: Myra
authors.initials: M
authors.lastname: Koesdjojo
authors.affiliation: Department of Chemistry, Oregon State University, Corvallis, OR 97331, USA.
authors.forename: Chadd
authors.initials: C
authors.lastname: Armstrong
authors.affiliation: Department of Clinical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, USA.
authors.forename: Shay
authors.initials: S
authors.lastname: Bracha
authors.affiliation: Department of Chemistry, Oregon State University, Corvallis, OR 97331, USA. Electronic address: vince.remcho@oregonstate.edu.
authors.forename: Vincent T
authors.initials: VT
authors.lastname: Remcho
mesh_terms: D002624:Chemistry, Clinical / Q000295:instrumentation*; D003124:Colorimetry; D005947:Glucose / Q000032:analysis*; D006801:Humans; D000068997:Smartphone; D014508:Urea / Q000032:analysis*
chemical_list: D014508:Urea; D005947:Glucose
keywords: Colorimetric analysis; Glucose; Point-of-care; Smartphone; Urea