Smart Skin for Composite Aircraft

The NASA technology can be used to protect tall structures from lightning strike damage. When a lightning leader propagates through the atmosphere in the vicinity of a tall structure, the lightning electromagnetic emissions generated from the moving electrical charge will impinge upon the tall structure before the actual charge attaches. As the lightning leader propagates closer to the tall structure, the radiated emissions at the tall structure will grow stronger. The SansEC sensor is designed to operate within the lightning radiated emission spectrum and thus is passively powered by the external oscillating magnetic field from the lightning itself. The sensor will resonate and generate its own oscillating magnetic and electric fields which have been demonstrated to influence lighting attachment and propagation.

The SansEC sensor system consists of multiple pairs of inductor-capacitor sensors with no electrical connections, which are placed throughout the material being monitored for damage. The sensors are embedded in or placed directly onto the surface of the material. Strains and breaks are detected by changes in resonant frequency read by the accompanying magnetic field data acquisition system. When pulsed by a sequence of magnetic field harmonics from the acquisition system, the sensors become electrically active and emit a wireless response. The magnetic field response attributes of frequency, amplitude, and bandwidth of the inductor correspond to the physical property states measured by the sensor. The received response is correlated to calibration data to determine the physical property measurement. Because each sensor pair has its own frequency response, when damage occurs to that circuit the frequency response changes. This change identifies the damage location within the material. A unique feature achieved by eliminating electrical connections is that damage to a single point will not prevent the sensor from being powered or interrogated. If a sensor is broken, two concentric inductively coupled sensors are created, thus identifying tamper or damage location.

The technology presents a fundamental change in the way electrical devices are designed, using an open circuit in conjunction with a floating electrode, or an electrically conductive object not connected to anything by wires, and powered through a wireless device. This system uses inductor-capacitor thin-film open circuit technology. It consists of a uniquely designed, electrically conductive geometric pattern that stores energy in both electric and magnetic fields, along with a floating electrode in proximity to the open circuit. When wirelessly pulsed from the handheld data acquisition system (U.S. Patent Number 7,159,774, Magnetic Field Response Measurement Acquisition System), the system becomes electrically active and develops a capacitance between the two circuit surfaces. The result is a device that acts as a parallel plate capacitor without electrical connections.

This technology is a method of identifying material anomalies and defects on or within a material by observing and quantifying how a localized change in either conductivity, permeability or permittivity changes the responding electric field and magnetic fields. This approach has many advantages over typical spectroscopy methods, particularly because typical methods only measure changes in the electric field. This advancement will allow for potentially deeper detection of a material's abnormalities/defects (including subsurface measurements) with limited electrical requirements. The technology has applications as diverse as medical oncology screenings or surface measurements of aeronautic skins. Another promising application is bore hole geological spectroscopy. In such an application, an array of sensors could be embedded into bore hole drills for exploratory deep wells. As the drill tooling slides past the bore hole wall, spectroscopic sampling of the side walls reveals important dielectric property information that is highly useful to prospectors and geologists in determining the probability of specific resources that may exist in the subterranean geology.

The FAA and Aircraft Industry recognize the need to reduce fuel tank explosion risk by eliminating ignition sources and changing fuel tank design and maintenance. This technology can be utilized to wirelessly sense the level of fuel in aircrafts, thus mitigating risk of inadvertent electrical failures and sparks. NO wires enter the fuel tank and the radio frequency transponder typically requires 10 milliwatts of power or less. The technology can be used for dielectric tanks, by simply applying the sensors to the tank surface (as pictured). Through certain techniques the technology can be applied on metal tanks with no wires entering the tank from the outside. Currently, there are more than 20,910 jet aircraft in service. This presents a large market opportunity for retrofitting this technology onto existing airplane fuel tanks Rapidly evolving aviation services are expected to spur worldwide requirement for 36,770 new jet aircraft by 2033. This presents a growing market for new installations.