| How it captures a fingerprint | Uses light and an image sensor to photograph the ridge-and-valley pattern, typically when a finger touches a scanning surface. | Uses an array of tiny capacitors to measure differences in electrical capacitance between fingerprint ridges and valleys. | Sends and receives high-frequency sound waves to map the fingerprint surface from reflected signals. |
| Typical image characteristics | Produces a two-dimensional image. Image quality depends on illumination, sensor resolution, and the condition of the contact surface. | Produces a detailed two-dimensional pattern and detects physical contact through electrical measurements. | Can capture surface detail and, depending on the sensor design, information about the subsurface ridge structure. |
| Performance with dry fingers | Often works well, though very dry skin or poor contact can reduce the clarity of the captured image. | May have difficulty when dry skin makes electrical contact less consistent; performance varies by sensor design. | Can work well with dry fingers, but results still depend on contact quality and the particular implementation. |
| Performance with wet fingers | Water, smears, or moisture on the sensor surface can reduce image clarity. | Moisture can affect readings and may cause unreliable captures, depending on the amount of water and sensor design. | May tolerate some surface moisture better than optical capture, but wet-finger performance is not guaranteed. |
| Surface contamination | Dust, oil, or residue can obscure the image and may require cleaning. | Residue or moisture can interfere with contact and affect readings; a clean surface is still important. | Can be less dependent on optical clarity, but dirt or poor acoustic contact can still affect capture quality. |
| Installation options | Commonly used in standalone readers and access-control devices; requires an optical path and a suitable scanning surface. | Can be built into compact touch surfaces and embedded devices; requires close finger contact with the sensing area. | Can be integrated under certain display or cover materials, subject to the sensor’s acoustic and mechanical design. |
| Durability considerations | Image quality may be affected by scratches, dirt, or wear on the exposed scanning surface. | Durability depends on the protective surface and construction; the sensing elements are typically integrated beneath the contact area. | Durability depends on the transducer, bonding layers, cover material, and overall assembly. |
| Integration and cost considerations | Often a straightforward option for dedicated reader hardware, but needs space for illumination and image capture. | Can support compact designs; cost and power use vary with sensor size, resolution, and electronics. | May require more specialized components and acoustic integration, which can increase design complexity and cost. |
| Security considerations | Security depends on the complete system, including presentation-attack detection, matching software, and enrollment controls. | Electrical sensing alone does not guarantee spoof resistance; system-level liveness checks and secure matching matter. | Additional fingerprint information may support liveness analysis, but spoof resistance depends on the implementation and testing. |
| Best suited to | Cost-conscious access-control installations and applications where a dedicated reader and regular surface cleaning are practical. | Compact devices and touch-based interfaces where a small, integrated sensor is a priority. | Designs that need under-cover integration or may benefit from richer surface information, when the added integration effort is acceptable. |