**8. Conclusions**

is due to the fact that the Load Cell contains a vacuum chamber where a complex and expensive circuit is located to stabilize the output signal and reduce the noises. In our sensor, we used a design which was as simple as possible since the sensor is designed for a wide range of consumers. Nevertheless, this design showed higher

The piezo-optical transducer operation was studied in detail theoretically, experimentally, as well as with the help of accurate numerical simulation. In order to compare the main parameters of sensors based on different physical principles, expressions for the gauge factors of strain-resistive, piezoelectric and fiber-optic sensors were proposed and analyzed. Despite the high piezoelectric modules of new piezoelectric materials (electroactive polymers), the piezoelectric sensor gauge fac-

It was shown that the piezo-optical sensor gauge factor, in contrast to sensors of other types, depends on the sensor design and can be improved by optimizing the PE design. The PE cruciform shape allows stresses to be concentrated in its small working volume because fused quartz used has no plastic deformation and the compressive damage threshold is very high. The piezo-optical quartz sensor gauge factor (7389), obtained by numerical simulation of stresses and deformations in the PE, is confirmed by the experimental results (7340) and is two to three orders of magnitude greater than the gauge factors of sensors based on other physical

**Table 2** shows that piezo-optical transducer is superior to the known industrially usable strain gauges. The high sensitivity of the piezo-optical sensor opens up new possibilities in problems of deformation measuring and stress analysis. For example, the use of only one such sensor makes it possible to control all parameters of the elevator movement: acceleration and deceleration, jerk, vibration, sound, according to International standard ISO 18738-1:2012 (E) Measurement of ride quality — Part 1: Lifts (elevators), as well as friction between the elevator car and the rails [45].

> **Strainresistive**

Gauge Factor (GF) 2–4 0,78 0,1–36 > 7000 Dependence of GF on sensor design no no no yes

Sensitivity to the relative deformation <sup>10</sup><sup>6</sup> <sup>10</sup><sup>6</sup> <sup>10</sup><sup>6</sup> <sup>&</sup>lt; <sup>6</sup> <sup>10</sup><sup>10</sup> Measurement error, % 0.05–0.1 0.25–1.0 — 0.01–0.03

Hysteresis, % 0.5 no no no Overload, % of nominal < 20 — — 300–1000 Parameters degradation yes no yes no Type of measured loads Dynamic, static Static Dynamic Dynamic, static

**Fiberoptic**

**Piezoelectric**

— — 80 1100–50,000

–10<sup>4</sup> 103 <sup>10</sup><sup>3</sup> <sup>&</sup>gt; <sup>5</sup> 104

**Piezo-optical**

**Parameter Sensor type**

Deformation-to-current transfer function

Dynamic range 10<sup>3</sup>

*Comparison of some basic strain sensors parameters.*

slope, μA/μm

**Table 2.**

**52**

sensitivity compared to the calibration Load Cell.

tors are similar to strain-resistive sensor gauge factors.

**7. Discussion**

*Optoelectronics*

principles.

The theoretical, technological and design foundations for the highly sensitive piezo-optical transducers creation for strain gauges have been developed. It has been shown experimentally that such sensors have:

