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Haptic Switch (MoJo 2)

MoJo 2 Application Example: 

Hypersensitive Switch with Haptic Feedback

  • Sub gram sensitivity
  • Auto zero
  • Auto sensitivity
  • Zero finger movement detection
  • No finger release from switch necessary
  • Haptic (vibration) or audio feedback


The Celtic Magic Haptic Switch system is based on the Celtic Magic MoJo 2 product.  At the core a MoJo is a hypersensitive measurement device that is capable of measuring sub gram forces, this can be fifty times more sensitive than the most sensitive of mechanical switches & buttons available today.   With such small pressures it is not possible for the user to know when a valid press has been successfully made, so a small haptic vibration device is built into the sensor indicates a successful press.  Alternatively, a buzzer can be connected to indicate the same.

One of the big challenges of extreme immobility is that the very limited muscle strength available can be below that necessary to actually move the finger at all.  Even touch sensors that require the user to lift a finger from the device can then prove difficult to use. 

The Mojo is designed to overcome this by allowing the finger to always rest on the sensor.  The weight of the finger is always present.  The MoJo measures this constant weight and much like a kitchen weighing scale will tare this to zero.  Any tiny additional force is then detectable, even if this is lower than is necessary to move the finger and will then activate a relay (switch) output via a 3.5mm socket.

This tare to zero feature is automatic and takes a second or two after the finger is rested on the sensor.  In addition, the MoJo measure the first trial ‘presses’ the user makes and auto calibrates the sensitivity to the users capabilities.     For example, if the user can manage a maximum press of say 10g the MoJo will activate at 25% of 10g (adjustable) ie 2.5g would represent a valid press.   However, if the user can only manage a maximum of say 2g then 0.5g will activate the switch output.

Both the tare and sensitivity calibrations are automatic and takes only a few seconds each time a switch is set up for the user.

The force sensor called a zSensor is supplied on small articulated arm mounted from a cushioned hand rest.  This allows for any angle and position to be achieved to suit whatever convenient movement the user has.     

The zSensor could alternatively be mounted to detect controlled movement from any part of the user’s body such as toes or facial muscles. 

Download pdf HERE

For more information please contact Celtic Magic