A Phototransistor-Based High-Sensitivity Biosensing System Using 650-nm Light

Yu Wei Chang, Yu Ting Tai, Yuh-Shyong Yang, Yang Tung Huang

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


A miniature optical biosensing system based on a PMOS phototransistor and absorption photometry is proposed. The phototransistor was manufactured in a standard 0.35-µm CMOS process, and it exhibited a responsivity higher than 1000 A/W for 650-nm light. For biochemical applications, the TMB/H2O2/HRP method was adopted as a useful basis in our system. A sample volume of only 10 µl was required to be dropped on the slide above the phototransistor. Experimental results demonstrated that a high sensitivity of 2.5 µ?/pM was achieved, and the minimum HRP concentration successfully detected was 2.7 pM. This detection limit is three orders of magnitude better than that of a lately reported silicon biosensor, and is even comparable to that of a commercial spectrophotometer.

Original languageEnglish
Pages (from-to)673-677
Number of pages5
JournalIEEE Sensors Journal
Issue number6
StatePublished - 1 Jan 2009


  • Biomedical transducers
  • medical diagnosis
  • photodetectors
  • phototransistors

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