Provided is a strain sensor. The strain sensor according to embodiments of the inventive concept includes a flexible substrate, rigid patterns on the flexible substrate, the rigid patterns including a first pattern and a second pattern spaced apart from the first pattern in a first direction, a first electrode on the first pattern, a second electrode on the second pattern, the second electrode being spaced apart from the first electrode, and a piezoresistive layer connecting the first electrode and the second electrode. Here, each of the rigid patterns may have a stiffness greater than that of the flexible substrate.

A multibend sensor is able to provide information regarding bending of the sensor data in a manner able to mitigate error propagation. A reference strip and a sliding strip are separated from each other by a spacer. Electrodes are located on the reference strip and the sliding strip. The bending of the multibend sensor will be reflected in the shifting of the sliding strip with respect to the reference strip and the measurements obtained from the electrodes.

An accelerator is an automobile accelerator. The accelerator includes a sensor configured to detect a force to press the accelerator. The sensor includes a flexible substrate and a resistor formed of a film containing Cr, CrN, and Cr.sub.2N, on or above the substrate. The sensor is configured to detect the force to press the accelerator as a change in a resistance value of the resistor.

Provided is a strain gauge including a substrate, a resistive body, and a metal sheet. The resistive body includes a sensing portion, a first connection portion, and a second connection portion. The metal sheet covers at least the substrate that is exposed between two connection sites to which wirings to an external circuit are respectively connected and provided respectively in the first connection portion and the second connection portion and the sensing portion.

A strain gauge includes a flexible substrate; a functional layer formed of a metal, an alloy, or a metal compound, on one surface of the substrate; and a resistor formed of material including at least one from among chromium and nickel, on one surface of the functional layer.

A novel direct-ink-writing (DIW) method for printing a strain gauge array circuit is disclosed. Firstly, the whole circuit is layered by a 3D printing method; a thin layer of insulating material is printed on the first circuit layer, instead of printing an insulating bridge, to form the second insulating layer; a part needing to contact the second insulating layer is not printed, but one through hole is reserved; the second circuit layer is then printed; the functional layer of the strain gauge is finally covered; the electrodes on the functional layer can contact the second circuit layer or can contact the first circuit layer through the through holes, which ensures that the functional layer contacts the two circuit layers, and also ensures the insulation in a cross part of a matrix circuit; the printing of the array strain gauge is effectively completed; and the stability of measurement is ensured.

A strain sensor includes a flexible substrate and a circuit disposed on the flexible substrate. The circuit includes an inductance to receive an excitation signal, the circuit being configured to generate a radio frequency response to the excitation signal via the inductance. The circuit includes an elongated trace coupled to the inductance and configured to bend and stretch longitudinally upon deformation of the flexible substrate. The elongated trace includes a non-uniformity configured such that the elongated trace deforms and tears at the non-uniformity and exhibits a non-linear increase in resistance as a tensile strain to which the elongated trace is subjected reaches a strain threshold. The non-linear increase in resistance modifies a characteristic of the radio frequency response of the circuit.

A strain gauge includes a flexible substrate, resistors each formed of a film that includes Cr, CrN, and Cr.sub.2N, and a functional layer formed of a metal, an alloy, or a metal compound, the functional layer being in a lower surface of the resistors. The resistors include a first resistor formed on or above a predetermined surface of the substrate; a second resistor of which a grid direction faces a different direction from the first resistor, the second resistor formed on or above the predetermined surface of the substrate or a surface parallel to the predetermined surface; and a third resistor formed on or above a surface adjacent to the predetermined surface of the substrate.

A system including strain sensors, transmission lines, and a common receive line is described. The strain sensors receive can receive signal(s) on the transmission lines. The information from the strain sensors is provided on the common receive line. The strain sensors are configured to be selectively activated to transmit information on the common receive line in response to a control signal.

A component is provided for a human-powered vehicle. The component includes a component body, a single substrate, a resistor, an electric wire, a signal processing unit, a signal output, and an electric power input. The single substrate is provided on the component body. The resistor is formed on the single substrate and forms a strain gauge with part of the single substrate. The electric wire is formed on the single substrate and electrically connected to the resistor. The signal processing unit is formed or directly mounted on the single substrate and electrically connected to the electric wire. The signal output outputs a signal from the signal processing unit. The electric power input is electrically connected to the signal processing unit and supplied with electric power from a power supply provided on at least one of the human-powered vehicle and the component body.