Effect of finger size on CapSense, Child user vs Adult user


Question: Is there a design impact for adult users versus a child user?

Response: The variation in fingers from person-to-person is mainly related to finger size. There is a small variation finger sensitivity due to the moisture in the skin, but this is a minor variation. Finger size is compensated for by threshold levels that the customer sets in the user module. Our best practice states that the threshold should be set using the smallest finger touching the sensor off-center. In practice, we do this by using a metal disk, such as a coin, or a small metal post. If the sensor works well enough with a small finger placed off-center, it will have excellent performance with a large finger placed at the center of a sensor. Read more about tuning in Application Note AN47456.