Abstract
Silicon p-n junction diodes emit low-intensity, broad-spectrum light near 1120 nm in forward bias and between 400-900 nm in reverse bias (avalanche). For the first time, we experimentally achieve optical absorption sensing of pigment in solution with silicon micro LEDs designed in a standard silicon-on-insulator CMOS technology. By driving a single LED in both forward and avalanche modes of operation, we steer it's electroluminescent spectrum between visible and near-infrared (NIR). We then characterize the vertical optical transmission of both visible and NIR light from the LED through the same micro-droplet specimen to a vertically mounted discrete silicon photodiode. The effective absorption coefficient of carmine solution in glycerol at varying concentrations were extracted from the color ratio in optical coupling. By computing the LED-specific molar absorption coefficient of carmine, we estimate the concentration (∼0.040 mol L-1) and validate the same with a commercial spectrophotometer (∼0.030 mol L-1). With a maximum observed sensitivity of ∼1260 cm-1mol-1L, the sensor is a significant step forward towards low-cost CMOS-integrated optical sensors with silicon LED as the light source intended for biochemical analyses in food sector and plant/human health.
Original language | English |
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Title of host publication | Proceedings IEEE Sensors, SENSORS 2020 |
Place of Publication | Piscataway, NJ, USA |
Publisher | IEEE |
Number of pages | 4 |
ISBN (Electronic) | 978-1-7281-6801-2 |
DOIs | |
Publication status | Published - 2020 |
Event | 2020 IEEE Sensors, SENSORS 2020 - Virtual, Rotterdam, Netherlands Duration: 25 Oct 2020 → 28 Oct 2020 |
Conference
Conference | 2020 IEEE Sensors, SENSORS 2020 |
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Country/Territory | Netherlands |
City | Virtual, Rotterdam |
Period | 25/10/20 → 28/10/20 |
Bibliographical note
Accepted Author ManuscriptKeywords
- Avalanche breakdown
- CMOS
- light-emitting diode
- Optical sensing
- Silicon