Iris scanners and fingerprint scanners are alternative (biometric) input devices for computers.
handheld scanner
A fingerprinting scan is a very common biometric device. There are also iris matching scanners for high tech security. @Nottingham YE$
The influence of biometric devices on either security or privacy will depend upon how they are used. Like any other device, biometric devices can be used appropriately or inappropriately. Does the use of a knife make you bleed to death? But then, maybe you will just chop vegetables.
Broadly, a "biometric device" is any device that measures a biological function or trait. As related to computers, biometric devices are used to control access and/or verify identity. Voice recognition, retinal scanners, palm/fingerprint scanners are all examples of biometric devices. A biometric scanner will take a picture (your fingerprint, your retina) and match it to a previous scan kept on file. Other types of biometric devices, such as voice recognition systems, will record your voice and compare the recording to a sample on file.
*winks*
Haylo
A biometric sensor is a device that measures unique biological characteristics, such as fingerprints, facial features, or iris patterns, to recognize individuals. These sensors are commonly used for security purposes, access control, and authentication in various applications.
A biometric lock is a security device that uses unique biological traits such as fingerprints, retina scans, or facial recognition to grant access. It provides a secure alternative to traditional locks that rely on physical keys or codes for entry.
Accu-Chek is the brand of blood-sugar testing devices, i.e. glucose meters used primarily by diabetics. It might be considered a "biometric device" in the sense that it measures a biological property, but usually the term "biometric" refers only to methods for uniquely recognizing humans based upon one or more intrinsic physical or behavioral characteristics. Since glucose levels in blood do not uniquely identify an individual, a glucose meter like those from Accu-Check would not be considered a biometric device.
biometric authentication device digital camera
Althogh there there are better biometric devices, face recognition is an example of biometric device because it has to recognize your face to authenticate you to a facility.
Most biometric devices would be input devices although they may also utilize storage devices and output devices in their functioning. A biometric device usually takes in biometric information about a person and compares it to information stored in a database - much like username/password methods of authentication compare the username and password to the stored information for a user. Fingerprint scanners, read the fingerprint, convert it to a data stream and then compare it to the stored data previously recorded for the individual, retinal scanners read information about the retinal patterns of a user, convert it to data and compare it to stored data, etc. Note that biometric devices must rely on a storage device, but usually the storage device is not part of the biometric device. Instances of OUTPUT associated with a biometric device might be a signal to open a door or trigger an alarm, but again, the output usually comes from another device that the biometric device is connected to.