The human skin hosts an array of sensors that are capable of detecting and interpreting many traits important to how we\ud
function and survive. The goal of mimicking this capability in composites to create intelligent composite materials has led\ud
to the development of a bio-inspired stretchable network composed of numerous micro-fabricated sensors capable of\ud
detecting multiple stimuli. The components of the network are small scale and flexible making the network embeddable\ud
within complexly shaped composite layups and flexible structures with minimal impact on the host structure. This paper\ud
outlines recent progress in ongoing work to develop the bio-inspired network in order to create intelligent composite\ud
materials
We have developed methods for creating a highly expandable temperature sensor network for distributed temperature measurement. Stresses and strains due to network expansion are minimized through finite element analysis. Through the use of a uniquely patterned polyimide substrate and wire pattern an expansion ratio of 1,000% is achieved and the electrical resistance of components is maintained from pre-expansion to full expansion. Platinum resistance temperature detectors and electrodes are integrated directly in the polyimide-based network through a non-standard micro fabrication process. Calibration and interpolation algorithms have been developed for temperature measurement. Real-time distributed temperature measurement has been achieved through this sensor network, and it has shown great potential to be integrated into composites
Magnetic biosensors have emerged as a sensitive and versatile platform for high performance medical diagnostics. These magnetic biosensors require well-tailored magnetic particles as detection probes, which need to give rise to a large and specific biological signal while showing very low nonspecific binding. This is especially important in wash-free bioassay protocols, which do not require removal of particles before measurement, often a necessity in point of care diagnostics. Here we show that magnetic interactions between magnetic particles and magnetized sensors dramatically impact particle transport and magnetic adhesion to the sensor surfaces. We investigate the dynamics of magnetic particles’ biomolecular binding and magnetic adhesion to the sensor surface using microfluidic experiments. We elucidate how flow forces can inhibit magnetic adhesion, greatly diminishing or even eliminating nonspecific signals in wash-free magnetic bioassays, and enhancing signal to noise ratios by several orders of magnitude. Our method is useful for selecting and optimizing magnetic particles for a wide range of magnetic sensor platforms.
An investigation was performed to develop appropriate techniques to design and fabricate (using complementary metaloxide semiconductor/micro-electro-mechanical systems technologies) highly stretchable networks of distributed sensors and organic diodes that could be stretched, and surface-mounted or embedded into polymeric materials to cover an area several orders of magnitude larger than its original size. Both analysis and experiments were performed to validate the design and fabrication methods. The techniques sought to reduce stresses due to network expansion, and a new spin-coated fabrication process was developed to enable high-resolution features in the network. Networks with temperature sensors and piezoelectric sensors were fabricated and tested to demonstrate functionality in advanced composite materials that are common in aircraft.
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