Close-up of a smartwatch processing a fingerprint scan.

How Do Fingerprint Scanners Work?

What is fingerprint scanning? The short answer is that fingerprint scanners take an image of a person’s fingerprint but in reality, the technology is more complex. Fingerprint scanning uses a biometric process, or measurement and analysis of a person’s distinctive physical characteristics, to electronically collect and store human fingerprints.

By identifying and authenticating a scanned fingerprint against a database of known fingerprints, fingerprint scanners can identify individuals, allow or deny people to access to a restricted area, operate a vehicle, permit the use of electronic equipment, open a cellphone app, and more.

Hospitals and Healthcare Facilities Integrate Fingerprint Scanners

Once only seen in futuristic movies and television shows, the use of fingerprint scanning has become a commonplace security measure in hospitals and healthcare facilities. Fingerprint scanners are used to grant access to buildings, obtain medical records, and identify patients.

According to a 2016 study by the ECRI Institute Patient Safety Organization (PSO), a nonprofit group that advocates for patient safety, inaccurate medical records, and patient misidentification has led to an increased number of medical negligence cases. The ECRI Institute found 13% of mistakes occurred during patient registration and at least 22% of errors involved people who received the wrong treatment or procedure.

Fingerprint scanning technology can help reduce errors because a patient needs to be physically present to validate their identity. When this is used in combination with encryption software, the patient’s secure medical record can be accessed when they are identified.

Healthcare facilities also use fingerprint scanners to secure access to their own networks, equipment, cloud-based services, work stations, rooms, and medical cabinets. The need for staff to use passwords and badges is eliminated and so is the security risk of losing a badge or insecure password.

Some nurses and doctors are even carrying around this technology in their pocket because it’s available on their cellphone or smart device. Secure texting apps used by medical staff, such as our HIPAA-compliant miSecureMessages app, can be accessed using the device’s fingerprint scanning capability.

Types of Fingerprint Scanners

There are four types of fingerprint scanners used for security and data protection: optical, thermal, capacitive, and ultrasonic.

Optical scanners are the oldest and simplest form of this technology. A photograph of the fingerprint is taken with a digital camera. While algorithms are used to distinguish unique patterns on the surface, the resulting image is only a 2D picture. A high-quality image of a fingerprint can be used to “trick” an optical scanner.

Thermal sensors use the same material from infrared cameras to detect temperature differences between the contact surface and fingerprint ridges and valleys to make a fingerprint image. The ridges of the fingerprint are measured and the valleys are not. One of the biggest issues with this type is typical ambient temperature is roughly the same as finger temperature so differences in temperature are not detected.

Capacitive scanners send electrical currents to record the complex pattern of ridges and valleys found on a person’s fingerprint. The resulting image records the depth of the valleys and height of the ridges so even a high-quality print image won’t trick the capacitive scanner because it’s flat. The capacitive scanner requires the person’s finger to actually be present in order to generate the image again for verification. Capacitive scanners are the most common kind of fingerprint scanner today.

Ultrasonic scanning is the latest in fingerprint scanning technology. High-frequency sound waves are used to penetrate the finger’s epidermal layer, enabling it to “see” beneath the outer layer of skin. Both an ultrasonic transmitter and receiver are used to produce an extremely detailed 3D image of the fingerprint.

Currently, ultrasonic scanning is expensive and slow - such highly detailed scans take time to capture. Prototypes are currently being tested for use in mobile devices.

Using Fingerprints for Identification and Security

Thumbprints were used as personal, identifiable seals in ancient Babylon (2300 B.C.E.) and references indicate that King Hammurabi (1792-1750 B.C.E.) had law enforcement officers take the fingerprints of people who had been arrested.

The first recorded instance of using fingerprints to actually solve crimes appears in a document from the Qin Dynasty (221 to 206 B.C.E.) entitled, “The Volume of Crime Scene Investigation – Burglary”, explaining how the Chinese used handprints as a form of evidence.

It is probably not a surprise that today, fingerprint scanners are used in police stations and by those in security industries, but other businesses are using them as well. The storage lockers at Universal Studios use fingerprints instead of physical keys or cards and Walt Disney World scans fingerprints when entering to combat ticket fraud. Some airports and stadiums use fingerprint scanners as a “fast pass” for people who want to avoid long lines.

The use of fingerprint scanners is becoming more mainstream. In the future, we may no longer need to carry keys, identification, or even wallets. Fingerprint scanning technology may offer a more convenient, secure tomorrow.