The Bend Sensor® product consists of a coated substrate, such as plastic, that changes in electrical conductivity as it is bent. Electronic systems connect to the sensor and measure with fine detail the amount of bending or movement that occurs. The single layer design of the Bend Sensor® eliminates many of the problems associated with conventional sensors such as dust, dirt, liquids, and heat and pressure affects. Over-laminates or over-molding may also be applied to the sensors for added environmental protection. Flexpoint Sensor Systems offers standard designs, and can also custom design and engineer a sensor that meets the dimensions and requirements of your application.

THE BEND SENSOR®

Frequently Asked Questions

How many cycles can the sensor endure?


Based on a test set up with a 90° bend on a ¼” [6mm] radius, the Polyimide based sensors will complete > 30 million cycles and Polyester based sensors will complete >10 million cycles.




What temperature range will the Bend Sensor tolerate?


A standard Bend Sensor will function constantly between 100°C and -40°C. With some modifications we are able to get to 200°C and to -60°C




How much voltage can you use?


This depends on the circuit used to read the sensor. We have used 12, 5 and ~3VDC in designs we have developed.




What types of resistance change are possible?


Change in resistance is a function of bend radius and angular deflection. The sensor will also change if stretched linearly. Changes greater than 100X are possible.




What kind of chemical exposure can the Bend Sensor handle?


The sensors have been soaked in gasoline, diesel fuel, DOT3 brake fluid, antifreeze, alcohol, motor oil, and colas without detrimental effects on the sensor. Solvents like acetone and methyl ethyl ketone will dissolve some of the inks and destroy the sensor.




How is the sensor read?


The sensor is basically a variable resistor. Typically it only has two leads. In a microprocessor based circuit the sensor is set up in a voltage divider and the change in voltage is read by the processor using an ADC. There are some processors that have an integrated current DAC to bias the sensor with a constant current. The voltage across the sensor is then measured using the microprocessor’s ADC.




What is the repeatability?


Under controlled circumstances it is about +/-3%




How does humidity affect the sensor?


Humidity will affect the sensor. It is very repeatable and predictable. Flexpoint has a patent issued based on using the sensor as a humidity indicator.




How far can I bend the sensor?


The bend radius is limited by the material the sensor is printed on. Once the elastic limits of the substrate are exceeded then the sensor is damaged.




What is the difference between the Bend Sensor and a Force Sensing Resistor (FSR)?


FSRs are multiple layers that interact with one another. The resting resistance is generally quite high if not open and when the layers are compressed together the resistance decreases. The Bend Sensor is a single layer construction. It starts at a relatively low resistance when flat and increases as it is bent.




What is the difference between the Bend Sensor and a Piezo Resistive Sensor?


Piezo Sensors typically will give a voltage output when it is bent. Once motionless the sensor gives no feed back until it is moved again. The Bend Sensor will hold its higher resistance value when bent and return to the lower resistance value when returned to its flat state.




Can the Bend Sensor measure change in both directions?


Yes, we have a bi-directional version that uses sensor material on both sides and has a three pin connection. This sensor will give you the resistance change in each direction independently.




Can the Bend Sensor be made with multiple sections?


Yes. Custom sensors can be individually monitored.




What material can the sensor be printed on?


Currently the Bend Sensor is printed on Polyester and Polyimide (Kapton) materials.




What is the maximum and mimum lengths and widths for custom Bend Sensors?


The minimum length is about .25” [6mm] plus the connector. The maximum length is equipment limited to 30” [760mm]. The width limitations are about .10” [2.54mm]




Can I arrange for a custom design and build of a sensor?


To arrange for a custom sensor please contact Flexpoint directly. You can then discuss your application and sensor design to fit your requirements. If necessary NDAs can be signed in advance.





© 2020 Flexpoint Sensor Systems, Inc.