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Tekscan Pressure and Force Measurement Technology

 

Tekscan technology is used in a constantly expanding variety of applications. Each application has a distinct set of requirements that are well matched to Tekscan's core technical capabilities and product offerings. Tekscan has developed matrix-based pressure sensing systems and single load cell configurations - the FlexiForce® product line. Tekscan's systems-based solutions provide our customers with superior results with modest capital investments. Our clients are presented with an integrated pressure and/or force measurement system that uniquely matches their specific needs, ensuring optimal system and sensor performance.

 

Sensors

Sensor Technology

Pressure Sensor Technology

Pressure Analysis Software

Data Acquisition, Display,

& Analysis Software

Pressure Sensor Technology

Data Acquisition

Data Acquisition Hardware

 

 

Tekscan technology encompasses four distinct areas: sensor technology, data acquisition hardware, processing and analysis software, and materials technology. Each of these areas has a number of patents, copyrights or patents pending supporting Tekscan's intellectual property claims.

 


High Resolution and Versatile Sensor Technology

 

At the heart of every Tekscan pressure measurement system is an extremely thin 0.004 in (0.1 mm), flexible tactile sensor. Sensors come in both grid-based and single load cell configurations, and are available in a wide range of shapes, sizes and spatial resolutions (sensor spacing). These sensors are capable of measuring pressures ranging from 0-15 kPa to 0-175 MPa. Each application requires an optimal match between the dimensional characteristics of the object(s) to be tested and the spatial resolution and pressure range provided by Tekscan's sensor technology.

 

Tekscan provides the highest resolution matrix-based products available on the market. Sensing locations within a matrix can be as small as 0.04 mm2(0.000064 in2); therefore, a one square centimeter area can contain an array of 248 of these locations. We have created sensors covering 256 square inches (1,600 square centimeters) with over 100,000 sensing locations. Our Virtual Sensor Array (VSA) allows the user to integrate several sensors into a uniform whole. The areas covered using this method can be significant. The pressure or force information derived from the sensor array is seamlessly displayed on your computer screen.

 

 

How A matrix Sensor is Made

 

The standard sensor consists of two thin, flexible polyester sheets which have electrically conductive electrodes deposited in varying patterns. The inside surface of one sheet forms a row pattern while the inner surface of the other employs a column pattern. The intersection of these rows and columns creates a sensing cell, or sensel. The spacing between the rows and columns varies according to sensor application and can be as small as ~0.5 mm. In use, the sensor is installed between two mating surfaces. Tekscan's matrix-based systems provide an array of force sensitive cells that enable you to measure the pressure distribution between the two surfaces. For a complete list of all Tekscan's standard sensors, refer to the sensor catalog.

 

Sensor Response

 

 

Tekscan Sensor Properties & Performance

 

Sensor grids are available in a wide range of shapes and sizes. They are also available in various pressure ranges from 0-14 kPa to 0-207 MPa. Custom sizes and sensitivities are also available. Typical system performance is shown in Figure 1. Resistance of the sensing elements (sensels) varies inversely with applied load. The system linearizes sensor output into digital counts, or “raw” values on a scale from 0-255. Calibration converts raw values into engineering units, such as psi or kPa.

 

 

 

 

 

Figure 1. Typical Sensor Performance

 

 

SENSOR PROPERTY STANDARD HIGH-TEMPERATURE*

Linearity <±3% <±1.2%
Repeatability <±3.5% <±3.5%
Hysteresis < 4.5% of full scale < 3.6% of full scale
Drift per log time 5% 3.3%
Lag Time 5 µsec TBD
Operating Temperature -40° to 140°F (-40° to 60°C) Up to 400°F (200°C)
Thinness 0.004 in (0.1 mm) 0.008 in (0.2 mm)
Sensel Density

Up to 1,600 per sq. in.

(248 per sq. cm)
Pitch as fine as 0.025 in.

(0.6 mm)

Up to 400 per sq. in.

(61 per sq. cm)
Pitch as fine as 0.050 in.

(1.27 mm)

Pressure Range

Up to 30,000 psi (207 MPa)

(dependent on sensor selection)

TBD
*Custom Production Run Required.

 

 


 

Data Acquisition, Display, & Analysis Software

 

Tekscan’s products function in both static and dynamic measurement environments. Our customers are interested in the temporal development of load profiles and peak load attainment, as well as the relaxation characteristics of materials. Each system is capable of sampling thousands of sensels per second; our standard I-Scan® system can sample 250,000 sensels per second. Tekscan also has higher performance systems which sample 100,000 sensels at 500 Hz - an astounding 50,000,000 sensels per second!

 

Tekscan’s high-speed systems are simplified matrices or single load cell configurations. The current maximum sampling rate for an integrated system is 20 kHz in a 44 load cell configuration. This high sampling rate is possible due to the extreme thinness and the relatively high spring constant of our sensor materials (a rise time of less than 20 microseconds). The ability to directly instrument the impact surface greatly enhances overall test accuracy. No other system solution is as adaptable and affordable.

 

 

 

Making this possible is Tekscan’s custom data acquisition hardware and software. The data acquisition software consists of low level sampling control, sensitivity adjustment, and signal processing. This software optimizes the performance of the system in the acquisition of force or pressure data from our matrix-based and FlexiForce® sensors.

 

With its Windows™-compatible software, the Tekscan system is simple to operate. Whether you choose a standard or a custom package, your system will respond quickly to your most important and frequent needs with graphically informative displays and intuitive operations.


 

Data Acquisition Hardware

 

Tekscan’s interface products employ sophisticated microprocessor based circuitry to control scanning sequence and frequency, adjust sensitivity, and optimize the performance of matrix-based sensors.

 

Figure 2 illustrates the sensing system and a simplified electrical schematic of the 8 bit electronics (255 levels) that scan the intersecting points of the sensor’s rows and columns and measure the resistance at each crossing point or sensel. The sensels are read in the presence of multiple contacts while simultaneously limiting the possible current flow through the device. Each sensel is represented by a variable resistor whose value is highest when no force is applied to it.

 

 

 

 

 

 

 

 

Figure 2. Electronics Schematic

 

SCANNING ELECTRONICS

VersaTek® Handle & 8-Port Hub

VersaTek 8 Port Hub and Handle

VersaTek® Cuff & 2-Port Hub

VersaTek 2 Port Hub and Cuff

Evolution Handle

Evolution Handle


Scanning Rate Up to 20,000 Hz Up to 750 Hz Up to 100 Hz
Operating Temperature -10° to 55°C (14° to 131°F) -10° to 55°C (14° to 131°F) -10° to 55°C (14° to 131°F)
Ambient Humidity 0 to 90% (non condensing) 0 to 90% (non condensing) 0 to 90% (non condensing)
Connection Type USB 2.0 USB 2.0 USB 1.1 or 2.0
Power Input: 100-240 V 5A 50-60 Hz, 1.2A Output: 12V, 5A

Input: 100-240V, 50-60 HZ, 1.0A

Output: 9V, 3A

USB Powered, 200mA, 1W
Size L x W x H

Handle: 137.9 x 57.2 x 33.5 mm

(5.43 in. x 2.25 in. x 1.32 in.)

Hub: 193.8 x 121.7 x 35.05 mm

(7.63 x 4.79 x 1.38 in.)

Cuff: 98.4 x 66.8 x 25.4 mm

(3.88 x 2.63 x 1.00 in.)

Hub: 146.0 x 119.4 x 34.3 mm

(5.75 x 4.70 x 1.35 in.)

137.9 x 57.2 x 33.5 mm

(5.43 x 2.25 x 1.32 in.)

Weight

Handle: 305 g (10.8 oz)

Hub: 370 g (13.1 oz)

Cuff: 106 g (3.7 oz)

Hub: 236 g (8.3 oz)

305 g (10.8 oz)
Cable Length

Handle to Hub: 4.57 m (15 ft) standard

Up to 30 m (100 ft) available

Hub to Host: 3 m (10 ft)

Cuff to Hub: 4.57 m (25 ft)

Hub to Host: 3 m (10 ft)

4.57 m (15 ft)