Thought Technology Ltd, Canada
Model: T7640
  • ForceTrac is a highly sensitive and accurate sensor capable of monitoring any force perpendicular to its surface through one of 3 attachments.
  • It can be used as an algometer with its rod attachment or as a manual muscle tester with a choice of flat or curved rubbercoated attachment.


ForceTrac with curved probe
ForceTrac with rod attachment

ForceTrac is a highly sensitive and accurate sensor capable of monitoring any force perpendicular to its surface through one of 3 attachments. The ForceTrac force transducer can read a force (compression only) within a range of 0-100 lbs.

With the rod attachment, ForceTrac is used to apply force to a localized point (algometer) or as a manual muscle tester. It measures the amount of force applied and sends the value to the encoder.


For instance, the examiner positions the ForceTrac transducer (see picture below) between the limb or body part where the resistance will be applied and the hand applying the resistance.

Forcetrac in use

The flat probe is recommended for the trunk and large limbs, while the curved probe is recommended for the head and thin limbs.


  • Dimensions : 93mm x 63mm x 25mm
  • Weight (spprox.) : 94g
  • Input range (force) : 0–100 lbf
  • Safe overload : 250 lbf
  • Accuracy : ± (0.1lbf + 5% of reading)
  • Zero-level output : 2.048V
  • Full scale output swing : 1V at 100 lbs load
  • Power supply : 7.26V
  • Algometer Attachment
  • Dimensions : 69mm x 11mm (diameter)
  • Weight : 14g
  • Material : Aluminum
  • Flat Tester Attachment
  • Dimensions : 9mm x 42mm (diameter)
  • Weight : 39g
  • Material : Neoprene
  • Curved Tester Attachment
  • Dimensions : 19mm x 42mm (diameter)
  • Weight : 52g
  • Material : Neoprene


Recommended Connectivity for Electrical Safety

Thought Technology recommends the use of TT Sensor Isolator ST9405AM when interfacing patient connected sensor(s) to line powered equipment(s) or devices.

Ten20The TT Sensor Isolator ST9405AM is an interface device providing medical grade electrical isolation between the patient connected sensors and the acquisition system. It provides the equivalent of Two Means of Patient Protection under IEC 60601-1, and supplies battery power to the sensors. Using this device ensures Thought Technology sensors are safely interfaced to the analog inputs of line-powered systems such as computers with DAQ cards.

Note that this device isolates only between sensors and the DAQ interface, not between different sensor channels.

The TT Sensor Isolator can interface up to 4 sensors to a DAQ card. TT Sensor Isolator can be connected to the DAQ card in two ways:

  • via two stereo jacks, or
  • via a DB-15 connector; a BNC interface cable (SA9409BNC) or a pigtail cable (SA9409PGT) can be provided with the unit.


For more detailed information on the Sensor Isolator 4∞, consult the Thought Technology Science Division website or contact the sales department or your distributor.
Division website or contact the sales department or your distributor.

Direct Connectivity for Electrically Isolated Systems

The following notes are provided for qualified users to directly interface Thought Technology sensors with external systems.

WARNING: If the sensor is interfaced to non-Thought Technology devices without the use of a TT Sensor Isolator SE9405AM, an elevated risk of electrical shock may be present. In particular, if a patient-connected sensor is connected to any line powered device(s) or equipment(s), it will be the responsibility of the qualified user to ensure the electrical safety in the setup and to ensure that the device or equipment provides sufficient isolation.

To interface with a sensor, a single sensor cable may be cut in half. Both sides can then be used to make custom interfacing cables by stripping the outer insulation of each required conductor. The sensor cable contains 4 color coded conductors. The table below shows the color coding and pin connector assignment.

Pin Color Code Function Note
1 metal (shield) ground Signal and power ground, connection required.
2 yellow auxiliary (sensor ID) No connection required.
3 green signal Sensor output signal
4 red sensor power Supply voltage, +7.26V referenced to ground. Note: sensor performance may be sensitive to supply voltage.

Sensor Graph


1. The nominal supply voltage for this sensor is 7.26V. The sensor can safely be used with a supply voltage of up to 9V.

Recommended Specifications for DAQ Hardware

  • Recommended resolution of 0.15mV (16-bit ADC over 10V span) or better
  • Minimum input range:
    • If connected via SE9405AM Sensor Isolator, choose 0-5V (unipolar) or ±5V (bipolar).
    • If directly connected to DAQ, choose ±5V (bipolar).

Simplified Transfer Function

Transfer FunctionConversion of voltage [V] to force [N]

Transfer FunctionConversion of voltage [V] to force [lb]

The simplified transfer function assumes the sensor is used with the Sensor Isolator, or the supply voltage provided in the user setup is 7.26V nominal.