Degradation of silicon photonic biosensors in cell culture media: Analysis and prevention

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Silicon photonic biosensors are being widely researched as they combine high performance with the potential for low-cost mass-manufacturing. Sensing is typically performed in an aqueous environment and it is assumed that the sensor is chemically stable, as silicon is known to etch in strong alkaline solutions but not in liquids with a pH close to 7. Here, we show that silicon can be affected surprisingly strongly by typical cell culture media, and we observe etch rates of up to 2 nm/hour. We then demonstrate that a very thin (< 10 nm) layer of thermal oxide is sufficient to suppress the etching process and provide the long-term stability required for monitoring cells and related biological processes over extended periods of time. We also show that employing an additional pH buffering compound in the culture medium can significantly reduce the etch rate.

Original languageEnglish
Article number#284328
Pages (from-to)1-8
Number of pages8
JournalBiomedical Optics Express
Issue number6
Publication statusPublished - 9 May 2017

Bibliographical note

© 2017, The Author(s).


  • Damage
  • Optical sensing and sensors
  • Protective coatings
  • Reflection

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