A measurement system may include a set of drive electrical contacts including a force electrical contact and a return electrical contact electrically coupled to a tested material, a measurement electrical contact electrically coupled to the tested material, a return node, a voltage source, and a control module. A circuit path between the voltage source and the return node may include a fixed resistor and the tested material. The control module may be configured to cause the voltage source to apply a voltage signal to the force electrical contact, cause a voltage drop across the fixed resistor to be measured, cause a measured voltage to be measured using the measurement electrical contact, determine a measured equivalent impedance of the tested material associated with the measurement electrical contact based on the voltage drop across the fixed resistor and the measured voltage, and determine whether the tested material includes a crack or other defect based on the measured equivalent impedance.

A measurement system may include a set of drive electrical contacts including a force electrical contact and a return electrical contact electrically coupled to a tested material, a measurement electrical contact electrically coupled to the tested material, a return node, a voltage source, and a control module. A circuit path between the voltage source and the return node may include a fixed resistor and the tested material. The control module may be configured to cause the voltage source to apply a voltage signal to the force electrical contact, cause a voltage drop across the fixed resistor to be measured, cause a measured voltage to be measured using the measurement electrical contact, determine a measured equivalent impedance of the tested material associated with the measurement electrical contact based on the voltage drop across the fixed resistor and the measured voltage, and determine whether the tested material includes a crack or other defect based on the measured equivalent impedance.

The disclosure describes techniques for detecting a crack or defect in a material.

A sensor has an at least partially conductive material to which plural conductive contacts are connected. A processor causes circuits to be formed between pairs of the conductive contacts to measure an electrical property of the material between the contacts, such as a resistance of the material. The processor conducts such measurements between plural pairs of contacts to determine a location of an influence on the material and produces an output indicating the location. The influence can be, for example, a disruption of the material or, where the electrical properties of the material are affected by strain, a strain of the material.

In one embodiment, reinforced soil is assessed using a non-contact method including positioning a reference electrode in close proximity to a surface of the soil without contacting the electrode to the soil surface, vibrating the electrode with a vibration generator, and measuring an electrical potential difference between the electrode and the soil surface, the potential difference being indicative of the condition of a portion of a reinforcement member positioned below the soil surface at the location of the electrode.

In one embodiment, reinforced soil is assessed using a non-contact method including positioning a reference electrode in close proximity to a surface of the soil without contacting the electrode to the soil surface, vibrating the electrode with a vibration generator, and measuring an electrical potential difference between the electrode and the soil surface, the potential difference being indicative of the condition of a portion of a reinforcement member positioned below the soil surface at the location of the electrode.

A device for accounting for environmental capacitances caused by an external object when detecting the presence and surface location of an electrically conductive coating on a transparent and/or translucent medium includes: a capacitive sensor that provides multiple capacitances; electronics that are responsive to the capacitances; an excitation source that generates a train of pulses, voltage or current to determine capacitances at the capacitive sensor; a selective indicator; and, a capacitive sensing plate that affects, or is affected by, the pulses, voltage or current from the excitation source.

A device for accounting for environmental capacitances caused by an external object when detecting the presence and surface location of an electrically conductive coating on a transparent and/or translucent medium includes: a capacitive sensor that provides multiple capacitances; electronics that are responsive to the capacitances; an excitation source that generates a train of pulses, voltage or current to determine capacitances at the capacitive sensor; a selective indicator; and, a capacitive sensing plate that affects, or is affected by, the pulses, voltage or current from the excitation source.

Described example user interface control apparatus includes a first structure, with a first side, conductive capacitor plate structures spaced along a first direction on the first side, a movable second structure with an auxiliary conductive structure, and an interface circuit to provide excitation signals to, and receive sense signals from, the conductive capacitor plate structures to perform a mutual capacitance test and a self-capacitance test of individual ones of the conductive capacitor plate structures to determine a position of the second structure or a user's finger relative to the first structure along the first direction.

Described example user interface control apparatus includes a first structure, with a first side, conductive capacitor plate structures spaced along a first direction on the first side, a movable second structure with an auxiliary conductive structure, and an interface circuit to provide excitation signals to, and receive sense signals from, the conductive capacitor plate structures to perform a mutual capacitance test and a self-capacitance test of individual ones of the conductive capacitor plate structures to determine a position of the second structure or a user's finger relative to the first structure along the first direction.