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Surface Force Mapping

When two surfaces come into contact with one another, forces are exerted at their interface. The forces are not uniform as a result of the rigidity, roughness, compressibility, and flatness of the two surfaces. Therefore, in many instances, it is important to quantify these forces since they play a role in the physical interaction between the surfaces. Surface Force Mapping is the technique used to quantify and locate the respective forces.

Surface force mapping can be performed using the Tactilus®, tactile surface sensor system Tactilus® is a matrix-based system, essentially an “electronic skin”, that records and interprets surface force distribution and magnitude between any two contacting or mating surfaces and assimilates that data collected into a powerful, yet user-friendly, Windows®-based tool kit.

Tactilus® uses piezoresistive sensors. These sensors are semiconductors whose resistivity changes due to applied mechanical stress. Each Tactilus® sensor is carefully assembled to exacting tolerances and individually calibrated and serialized. The architectural philosophy of Tactilus® is modular allowing for portability, easy expansion, and simultaneous data collection from multiple sensor pads. Tactilus® employs sophisticated mathematical algorithms and advanced electronic shielding techniques to maximize environmental immunity to noise, temperature, and humidity.

The Tactilus® Bodyfitter® system is used for full-body, surface force mapping. The blue, full-body sensor array (shown in Figure 1) measures the pressure (or temperature) distribution between a person’s body and the mattress surface. Mattress sensors are commonly used by manufacturers to help design their products for maximum comfort. Retailers use the devices to help customers select mattresses appropriate to their body types and weights. They are used in hospitals and nursing homes to determine whether patients are in their beds. Medical researchers have used the system to study the relationship of pressure and bed sores. Podiatry is another medical application for Tactilus®. In addition, Tactilus® sensors are used in cribs to monitor the motion of babies.

surface force pressure
Fig 1: Surface Force Mapping Using the Tactilus® Bodyfitter® Full Body Sensor

Tactilus® allows the flexibility of recording human interface pressure across multiple skin regions simultaneously. Bringing human factors and ergonomic engineering to a new level, Tactilus® aids the test or design engineer in optimizing the tradeoff often made between performance and comfort. For example, the Tactilus® Human Body Interface Sensor System performs surface force mapping to collect pressure magnitude and distribution data from across the surface of the human body. The US Army uses this system for designing their soldiers’ vests and body armor.

Industrial hygienists use surface force mapping to help fit personnel with protective face masks as shown in Figure 2. Individual Tactilus® Free Form® sensors are positioned as needed to monitor the forces between the mask and the wearer’s skin.

tactilus free form
Fig 2: Using the Tactilus® Free Form® Sensor System to Fit a Face Mask

Other combinations of Tactilus® sensors can be used in surface force mapping for seating design and testing, saddle design, analyzing golfers’ footwork during their swings, and simultaneously measuring the multiple forces applied to occupants of automobiles.