Magnetoresistive biosensors with on-chip pulsed excitation and magnetic correlated double sampling.

Giant magnetoresistive (GMR) sensors have been shown to be among the most sensitive biosensors reported. While high-density and scalable sensor arrays are desirable for achieving multiplex detection, scalability remains challenging because of long data acquisition time using conventional readout methods. In this paper, we present a scalable magnetoresistive biosensor array with an on-chip magnetic field generator and a high-speed data acquisition method. The on-chip field generators enable magnetic correlated double sampling (MCDS) and global chopper stabilization to suppress 1/f noise and offset. A measurement with the proposed system takes only 20 ms, approximately 50× faster than conventional frequency domain analysis. A corresponding time domain temperature correction technique is also presented and shown to be able to remove temperature dependence from the measured signal without extra measurements or reference sensors. Measurements demonstrate detection of magnetic nanoparticles (MNPs) at a signal level as low as 6.92 ppm. The small form factor enables the proposed platform to be portable as well as having high sensitivity and rapid readout, desirable features for next generation diagnostic systems, especially in point-of-care (POC) settings

Bio-inspired stretchable network-based intelligent composites

The human skin hosts an array of sensors that are capable of detecting and interpreting many traits important to how we function and survive. The goal of mimicking this capability in composites to create intelligent composite materials has led to the development of a bio-inspired stretchable network composed of numerous micro-fabricated sensors capable of detecting multiple stimuli. The components of the network are small scale and flexible making the network embeddable within complexly shaped composite layups and flexible structures with minimal impact on the host structure. This paper outlines recent progress in ongoing work to develop the bio-inspired network in order to create intelligent composite materials

Functionalization of stretchable networks with sensors and switches for composite materials

An investigation was performed to develop appropriate techniques to design and fabricate (using complementary metal-oxide 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

Bio-Inspired Stretchable Absolute Pressure Sensor Network

A bio-inspired absolute pressure sensor network has been developed. Absolute pressure sensors, distributed on multiple silicon islands, are connected as a network by stretchable polyimide wires. This sensor network, made on a 4’’ wafer, has 77 nodes and can be mounted on various curved surfaces to cover an area up to 0.64 m × 0.64 m, which is 100 times larger than its original size. Due to Micro Electro-Mechanical system (MEMS) surface micromachining technology, ultrathin sensing nodes can be realized with thicknesses of less than 100 µm. Additionally, good linearity and high sensitivity (~14 mV/V/bar) have been achieved. Since the MEMS sensor process has also been well integrated with a flexible polymer substrate process, the entire sensor network can be fabricated in a time-efficient and cost-effective manner. Moreover, an accurate pressure contour can be obtained from the sensor network. Therefore, this absolute pressure sensor network holds significant promise for smart vehicle applications, especially for unmanned aerial vehicles

Magnetoresistive biosensors with on-chip pulsed excitation and magnetic correlated double sampling.

Giant magnetoresistive (GMR) sensors have been shown to be among the most sensitive biosensors reported. While high-density and scalable sensor arrays are desirable for achieving multiplex detection, scalability remains challenging because of long data acquisition time using conventional readout methods. In this paper, we present a scalable magnetoresistive biosensor array with an on-chip magnetic field generator and a high-speed data acquisition method. The on-chip field generators enable magnetic correlated double sampling (MCDS) and global chopper stabilization to suppress 1/f noise and offset. A measurement with the proposed system takes only 20 ms, approximately 50× faster than conventional frequency domain analysis. A corresponding time domain temperature correction technique is also presented and shown to be able to remove temperature dependence from the measured signal without extra measurements or reference sensors. Measurements demonstrate detection of magnetic nanoparticles (MNPs) at a signal level as low as 6.92 ppm. The small form factor enables the proposed platform to be portable as well as having high sensitivity and rapid readout, desirable features for next generation diagnostic systems, especially in point-of-care (POC) settings

Functionalization of stretchable networks with sensors and switches for composite materials

An investigation was performed to develop appropriate techniques to design and fabricate (using complementary metal-oxide 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

High-Resolution Analysis of Antibodies to Post-Translational Modifications Using Peptide Nanosensor Microarrays

Autoantibodies are a hallmark of autoimmune diseases such as lupus and have the potential to be used as biomarkers for diverse diseases, including immunodeficiency, infectious disease, and cancer. More precise detection of antibodies to specific targets is needed to improve diagnosis of such diseases. Here, we report the development of reusable peptide microarrays, based on giant magnetoresistive (GMR) nanosensors optimized for sensitively detecting magnetic nanoparticle labels, for the detection of antibodies with a resolution of a single post-translationally modified amino acid. We have also developed a chemical regeneration scheme to perform multiplex assays with a high level of reproducibility, resulting in greatly reduced experimental costs. In addition, we show that peptides synthesized directly on the nanosensors are approximately two times more sensitive than directly spotted peptides. Reusable peptide nanosensor microarrays enable precise detection of autoantibodies with high resolution and sensitivity and show promise for investigating antibody-mediated immune responses to autoantigens, vaccines, and pathogen-derived antigens as well as other fundamental peptide–protein interactions