Is there a sensor which is capable enough to detect a large portion of our body's muscle contractions (must detect back, glutes, quadriceps, hamstrings, (calves)).

Sensors Biometrics
1

I want to build project which can detect if a certain muscle is contracted based on the contractions of the back muscles (it shouldn’t be hard to detect muscle activity on our legs or glutes if the sensor is placed on the our upper or lower back). The main requirement is that the project consists of only one sensor (meaning the system shouldn’t cover a lot of space on our body).

2

Take a look at our Myoware products/kits, especially MyoWare 2.0 Muscle Sensor Development Kit

It’s likely going to be VERY difficult to discern noise from signal at the surface for pathways that are quite a bit sub-surface and not inherently correlated to back contractions