Improved biosensor for measurement of progesterone in bovine milk

Michael Delwiche, Xinkui Tang, Robert Bondurant, Coralie Munro

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


A biosensor for on-line measurement of progesterone was designed and calibrated. The objectives were to develop an improved immunoassay sensitive enough to measure progesterone in milk at follicular phase concentrations in real-time, and to design a biosensor for implementation of the detection chemistry. Anti-progesterone antibody was coated on small disks of nitrocellulose membrane, which were inserted in the reaction chamber prior to testing. An antigen capture format was used with 5 minutes for binding and peroxidase-labeled progesterone as the competitor, and 3 minutes for substrate development with tetramethylbenzidine as the chromophore. The sensor was designed using micropumps and valves under computer control, and tested fluid volumes of about 1 ml. Output was read as the rate of change in optical density at 645 nm. An automated sampler was designed to draw a test volume at the start of milking from the long milk tube using a 4-way pinch valve. The system could execute a measurement cycle in about 10 min, and progesterone could be measured at concentrations low enough to distinguish mid-luteal phase cows (2-10 ng/ml) from follicular phase cows (<1 ng/ml). The 95% confidence interval for a 0.5 ng/ml reading was estimated to be 0.2 to 1.5 ng/ml.

Original languageEnglish (US)
Pages (from-to)1997-2002
Number of pages6
JournalTransactions of the American Society of Agricultural Engineers
Issue number6
StatePublished - Dec 1 2001


  • Artificial insemination
  • Cow
  • Dairy
  • Estrus
  • Lactation
  • Reproduction

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)


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