Light sensors

Sensor – (also called detector) is a converter that measures a physical quantity and converts it into a signal which can be read by an observer or by an (today mostly electronic) instrument.

standard types – pressure, temperature, resistance, strain, ionisation, voltage, current, frequency, conductivity, neutron flux, altitude, displacement, flow, volumetric, acceleration, vibration, harmonics, noise

sensor – A device that picks up information on physical or chemical conditions — such as temperature, barometric pressure, salinity, humidity, pH, light intensity or radiation — and stores or broadcasts that information. Scientists and engineers often rely on sensors to inform them of conditions that may change over time or that exist far from where a researcher can measure them directly. (in biology) The structure that an organism uses to sense attributes of its environment, such as heat, winds, chemicals, moisture, trauma or an attack by predators.

Some examples of sensors being used in unexpected places

  • Sensordrone – turns your Smartphone Into a Carbon Monoxide Detector, Non-Contact Thermometer, Gas Leak Detector, Lux Meter, Weather Station, Diagnostic Tool, Breath Analyzer,…
Circular saw blade
  • Table saw stop (video 4:10) – detects the presence of something conductive – like a finger, and stops the table saw blade instantly to prevent any damage to the object. Very specific senors can be incorporated into conventional tools, like a table saw to prevent injury to the operator. From an engineering standpoint, the braking system, is the “star” of the show. The super high speed camera captures the demonstration for examining the details of the event.
  • Hard-Hat Sensor Short-Circuits Carbon Monoxide Poisoning – wearable computing and prevention-through-design to develop a practical sensing and alarm system that can tell when a worker’s blood oxygen level is cratering and prevent carbon monoxide poisoning. The result was a standard construction hard-hat modified to include a non-invasive blood-oxygen monitor.

What’s the problem?
Smart bridges – structural-health-monitoring technology – information about the structural integrity and damages on a bridge

  • strength gauges measure the strength of connection between joints
  • fiber-optic sensors to detect deformation of certain damages in the structures
  • accelerometers efficiently measure the vibration of the bridges
  • modal analysis, signal processing, pattern recognition to detect changes in the vibration patterns in the bridge indicative of damages

That’s engineering

  • Active sensor – A sensor which instigates an action and then waits for a response – such as transmitting a signal and measuring the response when it comes back.
  • Closed Loop control – A feedback loop used to control a device.
  • Echo location – A process where the position of an object is determined by emitting a signal and seeing how long before that signal returns.

Engineering ideas

  • braking, high speed camera, accelerometer, strength guages

Do it
Here are some challenges for you to work on…

  • suggest some innovative uses for sensors to prevent injury
  • explore sensor technology. Compare and contrast the benefits and drawbacks for each

Learn more…

  • SawStop – video with amazing “time warp” sequences showing entire mechanism in slow motion at very high resolution. The videography is impressive.