Metamaterial based torque and shaft rotational speed sensor

A torque measurement system, comprising:

• an outer hollow rotational shaft having a first interior volume and configured to rotate about a rotational axis in a rotation direction;
• an inner hollow rotational shaft having a second interior volume and arranged in the first interior volume, wherein the inner hollow rotational shaft is configured to rotate about the rotational axis in the rotation direction;
• a center rotational shaft arranged in the second interior volume and configured to rotate about the rotational axis in the rotation direction,
• wherein the inner hollow rotational shaft is mechanically coupled to the center rotational shaft at a first coupling location via a first coupling structure, wherein a rotation of the center rotational shaft causes a rotation of the inner hollow rotational shaft via the first coupling structure,
• wherein the outer hollow rotational shaft is mechanically coupled to the inner hollow rotational shaft at a second coupling location via a second coupling structure, wherein the rotation of the inner hollow rotational shaft causes a rotation of the outer hollow rotational shaft via the second coupling structure,
• wherein at least one torque applied to the center rotational shaft is translated into a first torque-dependent angular shift between the outer hollow rotational shaft and the inner hollow rotational shaft about the rotational axis;
• a first metamaterial track mechanically coupled to the center rotational shaft and the inner hollow rotational shaft via the first coupling structure and configured to co-rotate with the center rotational shaft and the inner hollow rotational shaft, wherein the first metamaterial track is arranged at least partially around the rotational axis, and wherein the first metamaterial track comprises a first array of elementary structures;
• a second metamaterial track mechanically coupled to the outer hollow rotational shaft and configured to co-rotate with the outer hollow rotational shaft, wherein the second metamaterial track is arranged at least partially around the rotational axis, and wherein the second metamaterial track comprises a second array of elementary structures,
• wherein the first metamaterial track and the second metamaterial track are mutually coupled to each other by a first torque dependent coupling, thereby forming a first mutually coupled structure;
• at least one first transmitter configured to transmit a first electro-magnetic transmit signal towards the first mutually coupled structure, wherein the first mutually coupled structure is arranged to convert the first electro-magnetic transmit signal into a first electro-magnetic receive signal based on the first torque-dependent angular shift;
• and
• at least one first receiver configured to receive the first electro-magnetic receive signal.