Both color and proximity sensors have many medical device applications. But because of the negative effects on color sensing caused by infrared (IR) light, which is required for proximity sensing, the two features have not been combined in one sensor. As a result of advanced semiconductor process techniques and optoelectronics expertise, however, TAOS Inc. has introduced what it claims is the industry’s first color sensor with an on-chip IR blocking filter and proximity sensor.
When producing ambient light and color sensors, for example, the goal is often to match the human eye, which sees visible light, explains Todd Bishop, TAOS technical marketing manager, Europe. Able to respond to visible light, as well as to UV and near-infrared light, silicon sensors have typically been used for such functions. But to obtain an optimal, more-accurate color measurement, an IR filter is needed. In the past, Bishop notes, customers had to provide their own IR filters, which could be costly and mechanically difficult to incorporate. “But with the new technology, we can incorporate an IR filter onto the sensor itself, which lowers the system cost and size while offering improved accuracy,” Bishop says.
Proximity sensing, however, needs to use this blocked IR light, Bishop adds. Thus, TAOS’s new TCS3x72 sensor features IR sensors for proximity in addition to color sensors that block IR on the same chip’s integrated circuit. To solve this apparent conflict, the IR filter is localized only to the color-sensing photodiodes. It is also able to perform ambient light sensing (ALS), which is a technology offering brightness control on device screens to optimize viewing based on lighting conditions.
To simplify design options and minimize software development, TAOS has made the TCS3x72 series pin and register compatible. Software is provided as well to optimize the TCS3x72-series ALS, enabling light color temperature sensing. In addition, software driver support and evaluation modules help to accelerate product time to market.
The new technology could be employed in a number of medical device and diagnostic applications, according to Bishop. “Color sensors could be used to measure color for safety redundancy,” he says. “For example, an IV pump might need different flow rates, depending on the liquid. If the bags are color coded, a sensor can measure this and set the pump automatically.” Color sensors can also be employed in pulse oximeters to simultaneously measure the rate of change of blood flow and the oxygen level.
In the future, the proximity detection features of these sensors also have the potential to be used in virtual button applications, according to Bishop. Virtual buttons create a zone that a user can touch in lieu of a mechanical button or switch. “This could be beneficial in medical applications so that hands don’t have to touch a surface and spread germs on medical equipment, such as on an on/off or light switch,” Bishop says.