Semiconductor strain gauge transducer

DETAILED DESCRIPTION It is an object of the present invention to improve the accuracy of conversion and considerably expand the working temperature range of the semiconductor strain gauge transducer.
The foregoing object is attained by providing a semiconductor strain gauge transducer comprising a sensitive element which is a monocrystal sapphire substrate carrying epitaxial silicon strain gauges made of silicon of p-type conduction interconnected into a bridge or differential strain-sensitive circuit whose output is connected to an input of a signal conversion unit; which strain gauge transducer is characterized, according to the invention, in that the hole concentration in the silicon is 3.
5.
multidot.
10.
sup.
19 to 3.
multidot.
10.
sup.
20 cm.
sup.
-3.
If a d.
c.
current source is used to feed current to the strain-sensitive circuit, it is expedient that the hole concentration in the silicon should be (3.
5+9)10.
sup.
19 cm.
sup.
-3.
If a d.
c.
voltage source is used to power the strain-sensitive circuit, it is expedient that the hole concentration in the silicon should be (1.
8+3)10.
sup.
20 cm.
sup.
-3.
A strain gauge transducer of a simple design can ensure accurate measurements within a broad range of positive and negative temperatures if the sapphire substrate, which carries a strain-sensitive circuit powered by a d.
c.
source, should carry an additional strain-sensitive circuit powered by a d.
c.
voltage source; the outputs of both strain-sensitive circuits should be connected to an input of a signal conversion unit via a relay-type switching element whose control circuit contains an epitaxial thermistor of silicon with a hole concentration of 3.
5.
multidot.
10.
sup.
19 to 3.
multidot.
10.
sup.
20 cm.
sup.
-3, which thermistor is either located in a non-stressed zone or oriented in the strain-insensitive direction of the sapphire substrate.
The semiconductor strain gauge transducer according to the invention exhibits a number of advantages over conventional transducers.
It features an improved conversion accuracy and a much broader working temperature range of -200