History
Our DRAS® sensors were originally developed to be integrated with electronic displays to enable the next generation of fully interactive flexible display devices such as mobile phones, e-book readers, smart watches, smart clothes or large scale flexible TVs. It has been successfully integrated as a touchscreen with Plastic Logic's flexible displays in 2014. Our sensor can be used to detect common interactive gestures such as tapping, pinching, and swiping, to detect handwriting and to measure finger force.
Since then, our solution has evolved into becoming the most cost efficient tactile sensor technology in the world! We can make flexible tactile sensors on a wide range of materials, from plastic films to paper, measuring contact area, contact position, contact force and center of force with the processing power found in most low-cost microcontrollers.
Properties
DRAS
Tactile Sensors
Conventional
Tactile Sensors
Contact Area
Measurement
Inherent
Calculated
Spatial
Resolution
Great
Moderate
Force
Resolution
1024 levels
Up to 256 levels
Poor
Great
Stable
Output
Borderless
Yes
No
Yes
Yes
Flexibility
Immune to
Temp./ Hum. Variations
Yes
No
Transparency
Possible
Impossible
Yes
No
Pressure Distribution
Measurement
Sensor Size
Unlimited (Some
constrains may apply)
Generally limited to
under 1sqm
H/W
Complexity
Very Low
Very High
Frame rates
1 Hz to MHz
1-500 Hz
Very High
Very Low
Power
Consumption
Processing
Power
Very Low
Very High
(Computer)
System Cost
Low
Very High
DRAS Technology
The DRAS Sensor technology revolutionizes tactile sensing by overcoming the complexity and high cost of all competing technologies. This is achieved by avoiding the individual scanning of all sensing points. Instead, our solution can determine the contact length and width, its position and the overall force applied within the contact area using four wires only, no matter how dense or large the sensor is. As an example, our SOLEPAD sensor used for measuring foot sizes, contains 47,600 sensing points but it can be scanned in microseconds, using smartly designed matchbox-sized electronics and producing data that can be analyzed by low-cost microcontrollers as opposed to powerful desktop CPUs.
The basic sensor consists of two insulative substrates; each substrate carries an array of parallel electrodes interconnected through a resistive path. The substrates are then laminated together so that each set of electrodes is facing each other at a 90 degrees angle. The substrates are separated with a spacer pattern to prevent an electrical contact at the cross-sections of the electrodes when no pressure / force is applied. Each cross-section forms a sensing point, or sensel.
Tactile Sensors
Conventional tactile sensors consist of an array of force sensing elements, resistive or capacitive, whose operation is based on the scanning of each individual sensel of the sensor to create a detailed image of the pressure distribution under the area of contact; such systems require highly expensive and bulky scanning electronics, complicated sensor connectors and are prone to manufacturing defects. The greater the number of sensing points, the more complex, large and expensive the scanning hardware becomes. In addition, a lot of data is transmitted to a computer that needs to analyze the sensor information, apply the required correction / calibration algorithms and then display the tactile pressure image in real-time. Such tactile sensors offer too much information for many applications, at an extremely high cost. As a result, these conventional tactile sensor technologies have a very low adoption rate compared to their application potential.
Upon the application of force, the cross-sections under the contact area are shorted. The sensor is connected with four (4) wires to the interface electronics. The electronics will immediately detect the total contact area as well as its position and the total force applied. S/W can be used to detect different contact movements, to identify patterns or to collect time-based contact information.
Further, an innovative method has been developed to quadruple the spatial resolution of the sensor beyond the physical limits imposed by the manufacturing process used.
In addition, if extreme positional accuracy is needed, a further innovation has been developed to compensate for the manufacturing tolerances of the sensor and of parasitic resistances. As a result, the DRAS sensor provides a consistent digital accuracy and precision compared to the noisy analog output of all other tactile sensor technologies.
Due to the sensor’s principle of operation and the accompanying innovations, the sensor size or spatial resolution do not affect the sensor’s performance or speed of operation. There can be a few thousand or a million sensels all connected to the same electronics through the four (4) wire connection. The overall operation is extremely fast since the contact size / position data is determined using a fixed number of a few measurements and calculations.
Also, our sensor can be virtually borderless, extremely thin (100 μm), low power and highly flexible / rollable. The sensor is manufactured using printable electronic inks.
Finally, the DRAS sensors can be customized to meet the application’s requirements in terms of shape, size, resolution, accuracy, flexibility, cost without compromising the ease of interface.
Multiple patent applications have been filed and granted across the world. We are always looking for strategic partners interested in incorporating the DRAS technology into their next generation electronic products.
The following table summarizes our performance against all other conventional (array based) tactile sensors.
R&D CORE's Advanced Sensors Group has developed a revolutionary sensing technology (DRAS®) that allows the creation of large, flexible, multi-contact, force sensing touch sensors (tactile sensors). The technology is based on a Digital Resistive Area Sensing principle.