How to Make Bi-Directional FLEX SENSORS
FIGURE 3
Soldering
wire on
copper clad
laminates.
FIGURE 4. Resistive
material layered
on copper clad
laminate.
FIGURE 5. Copper clad
laminate layered on
resistive material.
FIGURE 6.
Acetate
added to
sandwich of
materials.
FIGURE 7.
Sandwiched
materials
inserted into
heat shrink
tubing.
FIGURE 8. Base
of materials
before being
inserted into
heat shrink
tubing.
Making the Bi-Directional
Flex Sensor
The resistive material is
sandwiched between the two copper
clad laminates. The copper sides of
the laminates are both facing toward the resistive material; see Figures 3,
4, and 5. If you solder the wires on the same side of the laminates, when you
assemble the sensor the wires will be positioned on opposite corners, allowing
the base of the sensor to lay flatter.
To this sandwich, we add the acetate strip, as shown in Figure 6.
The purpose of the acetate strip is to make the sensor more resilient and able
to spring back after it has been flexed.
This entire sandwich is inserted into the heat shrink tubing (Figure 7).
The base of the sandwiched materials is shown in Figure 8, just before it is
inserted completely into the heat shrink tubing.
We are almost finished. At each end of the heat shrink tubing, place a small amount of clear silicon sealer, (Figure 9).
Allow the sealer to dry according to its directions, usually around 24 hours.
FIGURE 9.
Adding clear
silicon sealer
to ends of
the flex
sensor.
The copper cladding material is
divided into two pieces 1/4” wide
x 4. 5” long strips and is easily cut
with scissors.
Solder about 6” of wire to one
end of each strip. You may find it
Most materials are easily obtained from electronic sources.
Images Inc., can supply the following materials
to get you started:
Parts List
Single-sided 6” x 2” laminated
copper; $2.50
5” x 4” resistive material; $2.50
4” x 5. 5” .010 acetate; $1
3/8” heat shrink tubing (one foot); $1
Available from
Images Scientific Instruments, Inc.
109 Woods of Arden Road
Staten Island, NY 10312
718-966-3694 Tel.
www.imagesco.com/sensors/
flex-sensor.html
easier to solder the wire to the strip if
you tin the bottom 3/8” of each strip.
Solder each wire to one corner side of
the strip. It doesn’t matter which side
you choose, just make sure you solder
both strips on the same side. Take
a look at Figure 2 to get a quick
overview of flex sensor construction.
Resistive Materials
There are a variety of resistive
materials available: cloth, plastic, and
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