Semiconductors: Transducers 350

acceleration

A rate at which an object's velocity increases. Acceleration occurs when a force changes an object's momentum.

active transducers

A transducer that can convert signals without using an external power source. Active transducers usually produce electrical outputs when a physical signal changes their inherent properties.

actuators

An inverse transducer that converts an input signal into a mechanical output signal. Actuators convert electrical signals into mechanical energy or force that causes other components to turn on or move.

all-electrical

A circuit or device without any moving, mechanical parts. All-electrical devices like semiconductor transducers are smaller, faster, and more reliable than electromechanical devices.

altitude

Height in relation to sea or ground level. Altitude can be measured indirectly using pressure transducers.

amperage

A measurement of the amount of current flowing in a circuit. Amperage is measured in amperes (A).

amplify

To electronically increase a signal's strength or amplitude. Photomultipliers amplify very low levels of light.

anti-lock braking systems

ABSs. A safety feature that prevents a vehicles wheels from seizing up during braking to provide better traction control. Anti-lock braking systems use Hall Effect sensors to detect the rotation of a vehicle's wheels.

automation

The use of mechanical systems that operate with limited human interaction. Traditional automation is being replaced by smart technology that can function entirely on its own.

autonomous guided vehicles

AGVs. A programmable and highly sophisticated, driverless vehicle, often integrated with sensor technology, that moves throughout a space. Autonomous guided vehicles can use photoresistors to travel along a line by detecting changes in the light around it.

avalanche photodiode

A semiconductor diode that uses the photoelectric effect to convert optical signals into electrical signals and that is designed to be used in reverse bias. Avalanche photodiodes are used in silicon photomultipliers.

barium titanate ceramic

BaTio3. A ceramic semiconductor compound composed of barium and metatitanic acid. Barium titanate ceramic is used as the base material for PTC thermistors.

battery management systems

BMSs. A computer that monitors, regulates, and coordinates the operations of a battery pack. Battery management systems use thermistors help to prevent overheating and thermal runaway.

cadmium telluride

CdTe. A crystalline semiconductor compound made of cadmium (Cd) and tellurium (Te). Cadmium telluride is often used in photovoltaic cells because it absorbs light.

capacitance

The ability to store an electrical charge. In capacitive pressure sensors, capacitance generally increases as pressure increases.

capacitive pressure sensors

A pressure transducer that detects changes in capacitance between two electrodes, which may include inflexible electrode plates, flexible electrode diaphragms, or a combination of both. Capacitive pressure sensors, such as those in touch screens, are sometimes considered semiconductor transducers.

cleanrooms

A room in which variables like temperature, humidity, and air pressure are controlled and maintained. Cleanrooms are required to follow ISO standards.

conductive

Relating to a material's ability to act as a medium for conveying electricity. A material's level of electrical conductivity depends on its atomic structure.

contaminants

Any element or substance that makes an environment, product, or research process impure. Contaminants include skin cells, water, air pollution, biohazards, and other undesired particles.

control unit

A computer or microprocessor. A control unit in an ABS monitors voltage from Hall Effect sensors to determine wheel speed and adjust braking pressure to prevent wheels from locking.

crystals

A solid material with atoms arranged in a highly organized and repeating structure. Many semiconductors are crystals and some are piezoelectric.

current

The flow of electricity. Current strength is called amperage and is measured in amperes (A).

diaphragm

A flexible electrode in some capacitive pressure sensors. The diaphragms bend under pressure, which increases the air pressure trapped between the electrodes and is converted into current.

doping

Enriching an intrinsic semiconductor with trace amounts of other elements to increase its conductivity or control other properties like resistance. Doping adds holes or free electrons to a semiconductor's atomic structure.

electrodes

A component in an electrical device that conducts electricity. Electrodes in capacitive pressure sensors are either rigid plates, flexible diaphragms, or a combination of both and conduct more current as the pressure applied to the electrodes increases.

electromechanical

Operating through a combination of electric and mechanical components. Electromechanical transducers are generally larger, less reliable, and less durable than semiconductor transducers.

energy

The ability to do work. Energy comes in many forms, including electrical, mechanical, thermal, and chemical energy.

flow rates

A measurement of the amount of fluid being moved in a certain amount of time. Flow rates can be detected by pressure transducers.

fluid

A state of matter that can flow. Fluids can be liquids or gases.

force

An influence, such as a push or a pull, that produces a change in an object's motion or state of rest. Forces can be converted to electrical signals by pressure transducers.

gallium

Ga. A silvery-blue, crystalline metal that is relatively soft at room temperature. Gallium is one of four common intrinsic semiconductors.

gamma rays

A form of high-energy electromagnetic radiation with a wavelength shorter than X-rays. Gamma rays have a wavelength of less than 10 picometers.

gases

A fluid without a fixed volume that can flow and fill the space it occupies. Gases like oxygen and carbon monoxide can be detected by transducers.

gear

A circular toothed component that engages, rotates, and transmits power to another circular toothed component when rotated. Like a gear, trigger wheels, such as those used to monitor wheel speed in ABSs, have teeth.

Hall Effect sensors

A semiconductor transducer that converts changes in the strength of a magnetic field into voltage. Hall Effect sensors must be perpendicular to the magnet and are used for speed, proximity, and position sensing applications.

Hall voltage

V_H. Electrical pressure created as a result of the Hall Effect. Hall voltage is produced when a Hall Effect sensor is exposed to a perpendicular magnetic field.

infrared

IR. A wavelength of light that is beyond, or longer than, red on the visible light spectrum. Infrared light has a wavelength between 780 nanometers and 1 millimeter.

input

Energy received by a transducer. Input energy can include electricity, heat, light, sound, pressure, and many other signals.

inrush current

The initial surge of electricity into a device when it is first energized. Inrush current can cause overcurrent conditions.

integrated circuits

ICs. A complete, miniaturized electronic circuit that contains a variety of components on a single piece of semiconductor wafer. Integrated circuits, also known as microchips or chips, include components like transistors, resistors, capacitors, and diodes.

inverse transducer

A transducer that converts electrical signals into a physical quantity. An inverse transducer may output light, sound, heat, force, or mechanical motion.

IR

Infrared. A wavelength of light that is beyond, or longer than, red on the visible light spectrum. IR light has a wavelength between 780 nanometers and 1 millimeter.

junction potential

The minimum amount of voltage that is required to pass electrons through the depletion region of a diode, photodiode, or Hall Effect sensor and turn it on. Junction potential varies based on the amount of energy required to excite the electrons from the valence state to the conductive state.

LED

Light-emitting diode. A semiconductor transducer that emits a narrow spectrum of light in a forward direction. LEDs are passive transducers that transform electrical signals into light.

light-dependent resistors

LDRs. A simple photocell that decreases in resistance as it receives more light. Light-dependent resistors, or photoresistors, are active and are primarily used to detect changing levels of light in applications that do not require high speed or resolution.

light-emitting diode

LED. A semiconductor transducer that emits a narrow spectrum of light in a forward direction. A light-emitting diode is a passive transducer that transforms electrical signals into light.

magnet

A metallic object or substance that possesses a force that attracts or repels certain metals like iron. A magnet attracts opposite charges and repels like charges.

magnetic fields

The area in and around a magnet in which a magnetic force exists. Magnetic fields exhibit the power of attraction and repulsion.

magnetic flux

The force that surrounds a magnet and exhibits the powers of attraction and repulsion. Magnetic flux is described as imaginary lines of force that exit the magnet's north pole and return to its south pole.

magnetoresistive sensors

MR sensors. A semiconductor transducer that changes resistance in response to changes in the angle of a magnetic field. Magnetoresistive sensors are passive transducers that detect parallel magnetic fields.

mechanical

Relating to the use of physical force. Mechanical outputs include force and motion and are produced by actuators.

mechanical energy

A combination of kinetic and potential energy resulting from an object's position or movement. Mechanical energy can be output by transducers.

metal oxides

A compound containing metal and oxygen. Metal oxides are used as base materials for NTC thermistors.

microcontrollers

A small computer contained on a single chip that controls the function of a device. Microcontrollers contain processors, memory, and input and output terminals.

mill

A machine that uses a rotating multi-point tool to remove metal from the surface of a workpiece. A mill may be operated either manually or by computer numerical control (CNC).

motor controls

Any device used to start, stop, or change the speed or direction of a motor. Motor control devices often use Hall Effect sensors to detect position and speed.

negative temperature coefficient

NTC. A thermistor that decreases in resistance as temperature increases. Negative temperature coefficient thermistors produce very precise temperature measurements and are common in applications that use digital thermometers.

optocoupler

A semiconductor transducer that transmits electrical signals between separate circuits using an LED and a photocell sensor. An optocoupler, or photocoupler, often uses a photodiode to sense IR light from the LED.

optoelectronic devices

A component that relies on the interactions of light and electronics to function. Optoelectronic devices include light-sensitive transducers and many other devices.

output

Energy released by a transducer. Output energy is often electrical signals.

overcurrent

An excess of amperage flowing through a circuit. Overcurrent conditions can raise temperatures and lead to overheating.

parallel

Extending in the same direction and equidistant at all points. Magnetoresistive sensors should be parallel to a magnet.

particle counters

A device that measures particles by passing air through a laser chamber that counts the number and size of particles in the chamber. Particle counters can help identify contamination trends and reduce contamination.

passive transducers

A transducer that requires an external power source to convert signals. Passive transducers are generally more expensive but also have higher resolution than active transducers.

perpendicular

Intersecting at right angles. Hall Effect sensors must be perpendicular to a magnet.

photocells

A semiconductor transducer that changes resistance depending on the amount of light it receives and outputs electrical signals. Photocells convert include photoresistors, photodiodes, and photovoltaic cells.

photocoupler

A semiconductor transducer that transmits electrical signals between separate circuits using an LED and a photocell sensor. A photocoupler, or optocoupler, often uses a photodiode to sense IR light from the LED.

photodiodes

A photocell that detects or measures light when enough light causes it to overcome its junction potential and conduct current. Photodiodes are passive transducers that are best for applications that require high speed and precision.

photomultipliers

PMs. A passive transducer that detects low levels of light and amplifies them to produce a signal that is large enough to use. Photomultipliers are available as electromechanical or semiconductor devices.

photons

A particle of light energy. Photons are absorbed by photocells.

photoresistors

A simple photocell that decreases in resistance as it receives more light. Photoresistors, or light-dependent resistors, are active and are primarily used to detect changing levels of light in applications that do not require high speed or resolution.

photovoltaic cells

A photocell that converts light energy into electrical energy. Photovoltaic cells, or solar cells, are used with photodiodes in solar panels.

physical

A non-electrical signal. Physical quantities include sound, heat, force, light, and mechanical motion.

piezoelectric

Having the ability to generate an electrical charge when subjected to mechanical stresses. Piezoelectric, or piezoresistive, crystals are used in some semiconductor pressure sensors.

piezoelectric pressure sensors

A semiconductor pressure transducer that naturally outputs an electrical charge in response to pressure. Piezoelectric pressure sensors use piezoelectric semiconductor crystals.

piezoresistive

Having the ability to generate an electrical charge when subjected to mechanical stresses. Piezoresistive, or piezoelectric, crystals are used in some semiconductor pressure sensors.

positive temperature coefficient

PTC. A thermistor that increases in resistance as temperature increases. Positive temperature coefficient thermistors are common in applications that require protection from extreme temperatures or overcurrent.

power source

A device that generates electricity, such as a battery. External power sources are required for passive transducers to operate.

pressure

A physical force applied to an object. Pressure is measured in pounds per square inch (psi) or Pascals (Pa).

pressure transducers

A device that detects changes in applied force and converts them into electrical signals. Pressure transducers include piezoelectric sensors, semiconductor strain gauges, and capacitive pressure sensors.

proximity

The presence or closeness of an object. Proximity transducers can detect objects without contacting them.

resistance

The opposition to the flow of electrical current. Resistance is measured in ohms (Ω).

resistive

Relating to a material's tendency to oppose the flow of current. The resistance of many semiconductors decreases as their temperature increases.

resistor

A device that restricts the flow of electric current. Resistors limit current flow and produce work such as heat or light.

resolution

The amount and quality of detail that can be distinguished by a transducer. Transducers with higher resolution produce more precise results and can distinguish between smaller changes in signals.

scattered

Having traveled off a straight path. Scattered light can indicate contamination in the air, where light that is more scattered indicates more contamination.

semiconductor

A material or element with an electrical conductivity level between that of a conductor and an insulator. Semiconductors are most commonly crystalline solids and can be made more conductive by doping.

semiconductor strain gauges

SSGs. A semiconductor pressure transducer that changes in resistance when deformed. Semiconductor strain gauges are passive transducers that convert resistance into an equivalent pressure measurement.

semiconductor transducers

An all-electrical device that uses the properties of a semiconductor material to convert one form of energy to another. Semiconductor transducers are generally smaller, more precise, and more durable than electromechanical transducers.

sensing range

The distance from which a sensor can still detect a signal. The sensing range of a magnetoresistive sensor is greater than that of a Hall Effect sensor.

sensors

A device that detects a change in an input signal and turns it into an output signal that can be measured and/or recorded. Sensors often convert physical signals like pressure, sound, heat, or light into electrical signals that can be collected as data.

series

An electrical route that has only one path. An avalanche photodiode and a resistor are connected in series in a silicon photomultiplier.

signals

Energy that varies over time and is used to carry information. Signals include changes in electrical energy, heat, light, sound, pressure, magnetic fields, and other stimuli.

silicon

Si. A blue-gray, nonmetallic, crystalline material that is hard and brittle. Silicon is the most common intrinsic semiconductor.

silicon photomultiplier

SiPM. A photocell that uses an avalanche photodiode and a resistor connected in series to detect low levels of light and amplify them. Silicon photomultipliers are very small and fast and are most common in scientific research applications.

solar cells

A photocell that converts light energy into electrical energy. Solar cells, or photovoltaic cells, are used with photodiodes in solar panels.

solar panels

A circuit of linked photovoltaic cells and photodiodes. Solar panels are powered by the sun and often very large.

south pole

The positive side of a magnet. Magnetic flux returns to a magnet's south pole and after exiting its negative north pole.

speed

The amount of time it takes for an object to travel a given distance. Speed is used to measure both linear and rotational movement.

stress

A force that attempts to deform an object. Stress causes the resistance of semiconductor strain gauges to change.

surge protectors

A device that protects electrical components from voltage spikes. Surge protectors often use PTC thermistors to detect the excessive heat caused by surges.

switching

Turning the flow of electricity in a circuit on and off. Switching multiple connected circuits on and off can be accomplished with an optocoupler.

tachometers

A device that measures the rotational speed of a shaft. Tachometers often use Hall Effect sensors to measure rotational speed.

temperature coefficient

The change in a material's resistance relative to changes in temperature. A positive temperature coefficient indicates that resistance increases as temperature increases, while a negative temperature coefficient indicates that resistance decreases as temperature increases.

thermistors

A semiconductor transducer that changes resistance in response to heat. Thermistors are available in negative and positive temperature coefficient types.

thermoelectric

Relating to a material's tendency to produce, restrict, or pass electricity as a result of a change in temperature. An important thermoelectric property of semiconductors is their tendency to change in resistance in response to changes in temperature.

transducers

A device that converts one form of energy into another form of energy. Transducers often transform input signals like heat or light into electrical outputs.

trigger wheel

A toothed disk used with a Hall Effect sensor in an anti-lock braking system to detect wheel speed. The trigger wheel's rotation changes the strength of the magnetic field, which the sensor can use to determine how fast the wheels are spinning.

ultraviolet

UV. A potentially harmful wavelength of invisible light that is below, or shorter than, violet on the light spectrum. Ultraviolet light has a wavelength between 100 and 400 nanometers.

valve

A mechanical device used to regulate the flow of liquid, gas, or other objects. A valve has movable parts that can be controlled by an actuator to open, close, or obstruct one or more openings or passageways.

velocity

The rate at which an object changes position in a specific direction. Velocity can be detected by pressure transducers.

vibration

A rapid, continued, repeated motion. Vibration in a machine or other structures can be detected by pressure transducers.

voltage

The electrical pressure or potential that causes current to flow in a circuit. Voltage is measured in volts (V).

X-rays

A form of high-energy electromagnetic radiation with a wavelength shorter than ultraviolet and longer than gamma rays. X-rays have a wavelength between 0.01 and 10 nanometers.