Researchers in the Netherlands have developed a near infrared NIR sensor system that can be used to identify the veins in a hand for biometric security and other medical applications.
The team at the Holst Centre in Eindhoven combined organic NIR photodiodes with an oxide thin-film transistor backplane and a focusing lens to create an NIR sensor measuring 2.4 x 3.6 cm, large enough to image the palm of a hand or multiple fingers at a distance.
The 500ppi resolution of the NIR sensor enables high-quality images of the vein pattern. In addition, the sensor achieves external quantum efficiency (EQE) of 40 percent at 940 nm and a dark current of around 10-6 mA/cm2. The researchers see the sensor being integrated into a smartphone for identification as vein patterns are unique.
“Together with a NIR light source, the prototype image sensor opens the door to contactless biometric security through vein pattern detection. Our thin-film technologies make for extremely thin and potentially flexible sensors that could be easily integrated into existing displays and things like mobile phones or cash machine screens, eliminating the need for separate ID and credit cards,” said Daniel Tordera, Senior Scientist at Holst Centre.
Having demonstrated the potential of the large-area NIR sensor for vein detection, the researchers at the centre, a joint venture between imec in Belgium and local research house TNO, are pushing the sensitivity deeper into the NIR region.
With photodiodes efficient up to 1100 nm, these latest developments could enable new applications such as eye tracking, quality control in food production, condition monitoring of pipes and non-invasive in-body medical imaging including large area oxygen saturation (SpO2) measurements, conformable optical brain scans and cuffless blood pressure monitoring.
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