Wearable sensors are useful in the field of robotics, rehabilitation, biomechanics and medicine. In this work, we present a wearable measurement system equipped with a flexible, stretchable and tactile sensors array. The system contains four strain gauges connected to four separate Wheatstone bridges. The strain gauges were embedded into silicone Dragon skin to ensure the necessary properties of a stretchable sensor. We demonstrated the use of the developed wearable bio-instrument for detecting contractions of the subject's biceps muscle by tracking the angular motion of the elbow. The measurements showed good repeatability of the peak amplitude and demonstrated the possibility of detecting wirelessly the different angles of elbow flexion.