Piezo Haptics Lexicon

Learn the technical vocabulary behind piezo haptics, solid-state buttons and haptic actuators. Use the search bar to find a term.

Last updated: November 2026

  • Acceleration

    Acceleration is the rate of change of the velocity of an object with respect to time.

    It is normally measured in meters per second squared (m/s2). In haptics, acceleration is expressed in g, where 1 g equals the gravitational acceleration on Earth (9.8 m/s2).

    Source: Wikipedia, Acceleration

  • Actuator

    An actuator is a component of a machine that moves and controls a mechanism or system.

    In haptics, the actuator is the component that creates the vibration or click the user feels. The three main types are the ERM, the LRA and the piezoelectric actuator. Compare them in Piezo vs LRA vs ERM: How to Choose a Haptic Actuator.

    Source: Wikipedia, Actuator

  • Bandwidth

    Bandwidth is the difference between the upper and lower frequencies in a continuous band of frequencies. It is measured in hertz (Hz).

    In haptics, bandwidth is the frequency range where an actuator delivers good tactile feedback. A piezo actuator covers about 1 to 400 Hz. An LRA works efficiently only in a narrow band around its resonant frequency.

  • CapDrive

    CapDrive is the piezo driver architecture developed by Boréas Technologies for haptic actuators.

    CapDrive drivers deliver the high voltage a piezo actuator needs, up to 190 Vpk-pk, recover energy after each actuation and can use the actuator for force sensing. The Piezo Haptic Driver IC Selection Guide lists the CapDrive driver family. Read more in What Is CapDrive?

  • Damping

    Damping is an influence within or upon an oscillatory system that reduces, restricts or prevents its oscillations. In physical systems, damping comes from processes that dissipate the energy stored in the oscillation.

    The damping ratio describes how fast oscillations decay after a disturbance. A mass hanging from a spring, pulled and released, bounces up and down and overshoots its rest position on each bounce. The damping ratio measures how quickly those bounces die out.

    Source: Wikipedia, Damping ratio

  • Driver

    In electronics, a driver is a circuit or component used to control another circuit or component.

    A haptic driver turns a digital command into the signal that moves the actuator. A piezo actuator needs a dedicated high-voltage driver, which also sets the start-up time and power consumption of the haptic system.

    Source: Wikipedia, Driver circuit

  • Eccentric Rotating Mass (ERM)

    An eccentric rotating mass (ERM) is a haptic actuator made of an off-center mass mounted on the shaft of a DC motor.

    As the motor spins, the unbalanced mass shakes the whole device. ERMs are low cost and simple to drive, but slow to start and stop, and their frequency and strength cannot be set separately.

  • Energy Recovery

    Energy recovery is the reuse of energy that would otherwise be lost after each actuation.

    A piezo actuator behaves like a capacitor: it stores electrical charge when it is driven. A CapDrive driver recovers that charge after each actuation and reuses it for the next one, which lowers the power consumption of the haptic system.

  • Engine

    An engine or motor is a machine designed to convert one form of energy into mechanical energy.

    Source: Wikipedia, Engine

  • Fall Time

    Fall time is the time taken for the amplitude of a pulse to decrease from a specified value.

    In haptics, fall time is the time the actuator takes to return to rest from full amplitude. A short fall time makes a click feel crisp instead of buzzy.

    Source: Wikipedia, Fall time

  • Force

    A force is any interaction that, when unopposed, changes the motion of an object.

    A force can cause an object with mass to change its velocity, including starting to move from rest. A force has both magnitude and direction, which makes it a vector quantity. It is measured in newtons (N) and represented by the symbol F.

    Source: Wikipedia, Force

  • Force Sensing

    Force sensing is the measurement of how hard a user presses on a surface.

    In a piezo haptic system, the piezo actuator can also act as the sensor, because pressing it generates an electrical charge. CapDrive drivers such as the BOS1921 can read that charge, so the same actuator detects the press and delivers the click. The BOS1921-KIT-C03 lets designers test this on a solid-state button.

  • Frequency

    Frequency is the number of occurrences of a repeating event per unit of time.

    In haptics, frequency is the number of voltage cycles applied to the actuator per second, measured in hertz (Hz).

    Source: Wikipedia, Frequency

  • Haptic

    The word haptic, from the Greek ἁπτικός (haptikos), means "relating to the sense of touch". It comes from the Greek verb ἅπτεσθαι (haptesthai), "to touch".

    In technology, haptic feedback transmits information to the user through vibrations, impulses or movements. It is used in smartphones, game controllers, laptops, wearables and any device with a user interface.

    High-definition haptic feedback can create textures and detailed clicks. Boréas piezo driver technology lets system integrators add high-definition haptic feedback while reducing power consumption.

  • Haptic Latency

    Haptic latency is the delay between a user action and the moment the user feels the feedback.

    An LRA needs about 25 ms to reach its resonant frequency, which users feel as a slight lag. In Boréas bench measurements, a piezo actuator driven by a CapDrive driver starts within 0.3 ms.

  • Haptic Trackpad

    A haptic trackpad is a touchpad with no mechanical click that senses the press and uses actuators to simulate a click.

    Both LRA and piezo actuators are used. Piezo designs respond faster, which makes the surface feel more responsive. See how Boréas piezo haptics power the Framework Laptop 13 Pro trackpad.

  • Linear Resonant Actuator (LRA)

    A linear resonant actuator (LRA) is a haptic actuator made of a magnetic mass on a spring, moved by a voice coil at its natural resonant frequency.

    LRAs are common in smartphones for notifications. Because they work near a single resonant frequency, clicks made with an LRA can feel like a short buzz.

  • Localized Haptics

    Localized haptics is haptic feedback felt only where the finger touches, instead of across the whole device.

    Piezo actuators produce localized haptics because they move the surface directly under the contact point. ERM and LRA actuators usually vibrate the whole device. Localized haptics matter most where whole-device vibration is unwanted, such as a button on the temple of a pair of AI glasses.

  • Mass

    Mass is both a property of a physical body and a measure of its resistance to acceleration when a net force is applied.

    The SI unit of mass is the kilogram (kg).

    Source: Wikipedia, Mass

  • Piezoelectric Actuator

    A piezoelectric actuator is a haptic actuator made of a ceramic element that bends when voltage is applied, based on the piezoelectric effect.

    Piezo actuators respond in a fraction of a millisecond, cover a wide bandwidth and keep the feedback local. They need a dedicated high-voltage driver.

  • Piezoelectric Effect

    Piezoelectricity is the electric charge that accumulates in certain solid materials in response to applied mechanical stress. The word means electricity resulting from pressure.

    The effect is reversible. Materials that show the piezoelectric effect also show the reverse piezoelectric effect: they deform when an electric field is applied. Piezo haptics use the reverse effect to create motion and the direct effect for force sensing.

    Source: Wikipedia, Piezoelectricity

  • Resonance

    Resonance is the amplification that occurs when a periodic force is applied at a natural frequency of the system it acts on.

    At a resonant frequency, a system oscillates with a higher amplitude than when the same force is applied at other frequencies. Small periodic forces near that frequency can produce large oscillations, because the system stores vibrational energy.

    Source: Wikipedia, Resonance

  • Rise Time

    Rise time is the time a signal takes to go from a low value to a high value. It measures how well a circuit responds to fast input signals.

    In haptics, rise time is the time an actuator takes to reach full amplitude from rest. See also fall time and haptic latency.

    Source: Wikipedia, Rise time

  • Solid-State Button (SSB)

    A solid-state button (SSB) is a button with no moving parts that senses a press and uses an actuator to simulate a click.

    With a piezo actuator under the surface, the click is felt where the finger touches. The response is defined in software, so one surface can act as a button, a slider or a two-step control. The designer chooses the sensing method. Learn more on the Solid-State Buttons with Piezo Haptics page.

  • Waveform

    The waveform of a signal is the shape of its graph as a function of time. In electronics, the term usually applies to varying voltages, currents or electromagnetic fields.

    In piezo haptics, the waveform is the voltage applied to the actuator over time. Shaping the waveform changes how a click, a texture or an alert feels.

    Source: Wikipedia, Waveform