Event Switches for gait and biomechanics

Our flexible event switch is a true membrane switch designed by Motion Lab Systems for use in Biomechanics, Gait and Motion laboratories to detect gait events in ambulatory subjects. It consists of a durable 25mm diameter membrane switch with a 15mm sensor area on a 100mm flexible tail. The entire switch sensor is only 1mm thick, weighs less than 1gm, and responds reliably to 200gm of pressure applied anywhere in the sensor area.

This innovative design allows the event switch to be placed underneath any part of the foot, while maintaining a reliable connection to data recording equipment (via an industry standard BERG connector) safely away from any weight-bearing part of the limb. It is reliable in general use with most customers achieving a minimum of 10,000 actuations before failure.

The low mass and profile of these event switches means that they can be used under almost any gait condition without affecting the gait of the subject in any way – unlike the traditional insole event switches which add considerable mass to each foot as well as affecting the subject's ground contact sensation.

The small size of the sensor allows for flexibility in placement on the subjects' foot – making it much easier to accurately define gait events in human subjects as the sensors can be placed on any part of the foot that comes in contact with the floor. Many labs use a pair of switches on each foot to determine heel contact and toe contact timing allowing the gait cycle of the subject to be divided into the initial contact, stance, push-off and swing phases without any additional hardware. While most biomechanics studies are performed barefoot, these event switches can also be used either inside or outside of most shoes to detect basic gait events.

The Motion Lab Systems MA-153 event switches offer increased reliability when compared to FSR footswitch sensors and are easier to place on the subjects foot.

Our event switches are reliable replacements for FSR foot switches used with the ZeroWire system (Aurion, Cometa and Noraxon) as well as many other EMG and foot switch systems.

In addition, the low cost of these switches as compared to insole units, can significantly reduce the cost of individual tests as one set of Motion Lab event switches can accommodate any foot size or foot geometry. Furthermore, while these event switches are very reliable, it is easy to replace any individual switch should one break during a test.

We stock event switch interconnection cables that enable these event switches to be used with any of our EMG systems, together with individual connector cables that are suitable for the experimenter.

The MA-153 switch replaces the MA-150, 151 and 152 "FSR" event switches which are no longer available. Unlike "FSR" switches, the MA-153 event switch is a mechanical switch which improves the lifetime and reliability over the Force Sensitive Resistor (FSR) switches commonly used by other manufacturers systems.

Note that under severe overload conditions ( >100 psi applied to the switch alone for more than one or two seconds) the switch may not immediately open when the pressure is removed, resulting in longer closure dwell than the switch actually experiances. This situation does not arise in normal gait studies and only affects the closed to open switch phase.

Weight (including BERG connector) < 1gm
Actuation Pressure < 200gm
Lifetime ~10,000 cycles
Sensor area 15mm diameter
Sensor size 25mm diameter
Flexible tail length 100mm
Connection 2-pin female BERG