A demonstrator for vein detection has been launched at Holst Centre, based on in-house technology. The project already led to large area fingerprint scanners, a technology so sensitive that heartbeats can be visible on the screen of the fingerprint scanner. The near-infrared (NIR) vein detector takes it a step further. It can look deeper into the body than the fingerprint scanner because it identifies the blood running through the veins. Like this, patterns of people’s veins can be measured.
Advantages of organic-based photodetectors
Organic-based photodetectors (OPDs) have always attracted a lot of interest due to their advantages over current inorganic solutions, such as large-area processing, compatibility with flexible and even conformable substrates, low-cost fabrication and wavelength tunability. Particularly, there is a specific interest in near-infrared (NIR) OPDs, as there is a wide range of applications beyond the visible spectrum, and not many available convenient solutions. Applications range from human-machine interface (HMI) biometrics and healthcare to quality control and sensing in industries such as automotive and aerospace.
This new NIR vein detector displays the progress on NIR OPDs from material to optimized device stack and demonstrates a prototype for a specific application: biometric vein recognition.
State-of-the-art NIR OPDs
The findings of the developing team have led to state-of-the-art NIR OPDs. Daniel Tordera, Project Manager and Senior Scientist at Holst Centre, explains: “Our NIR OPDs excel in all of the PD figures of merit: a low dark current, a high external quantum efficiency and a high detectivity at the wavelengths of interest. The values are amongst the highest ever reported. This NIR OPD frontplane array did combine this with a high resolution 500 ppi oxide TFT backplane to create a large-area detector. The detector has been characterized, showing high uniformity and linearity, to work under a wide range of lighting and ambient conditions. Using a NIR light source -850 and 940 nm- the detector is capable of imaging the veins under the skin over large area in reflection. The veins on the palm and wrist are imaged and their patterns are extracted to allow for biometric identification of subjects. Moreover, the system is capable of recording a heartbeat and photoplethysmogram (PPG), and thus allows for liveness detection and hence a more secure authentication.”