Wireless microsensors have been an innovative means for environmental monitoring as they enable users to measure spaces that were earlier off the limits of study—for example, remote areas in the human body, vehicle components, or toxic areas.
However, the efforts of scientists have been thwarted by restricted improvements in the quality of data and sensitivity of these devices due to difficulties attributive to the environments they function in and the demand for sensors that have extremely small footprints.
In a new paper published in Nature Electronics on May 14, 2018, scientists from the Advanced Science Research Center (ASRC) at The Graduate Center of The City University of New York, Wayne State University, and Michigan Technological University have elucidated the way new devices that have potentials much more than traditional sensors can be developed by borrowing concepts from quantum mechanics.
The team, headed by Andrea Alù, director of the ASRC’s Photonics Initiative and Einstein Professor of Physics at The Graduate Center, and Pai-Yen Chen, a professor at Wayne State University, devised an innovative method for developing microsensors, which enables considerably improved sensitivity and a very small footprint. In the new technique, isospectral parity-time-reciprocal scaling, or PTX symmetry, is used to develop the electronic circuits. A “reader” is paired with a passive microsensor that satisfies the PTX symmetry. The pair realizes highly sensitive radio-frequency readings.
In the push to miniaturize the sensors to improve their resolution and enable large-scale networks of sensing devices, improving the sensitivity of microsensors is crucial. Our approach addresses this need by introducing a generalized symmetry condition that enables high-quality readings in a miniaturized footprint.
The study builds on latest progress in the field of optics and quantum mechanics, which have demonstrated that systems symmetric under time and space inversion, or parity-time (PT) symmetric, might prove to be beneficial for sensor design. In the paper, this property is generalized to a broader category of devices that meet a more general form of symmetry - PTX symmetry. This form of symmetry is specifically best suited to preserve high sensitivity, while dramatically minimizing the footprint.
The team could demonstrate this phenomenon in a telemetric sensor system based on a radio-frequency electronic circuit, which displayed considerably enhanced sensitivity and resolution in comparison with traditional sensors. The micro-electromechanical (MEMS)-based wireless pressure sensors share the sensitivity benefits of earlier PT-symmetric devices; however, critically, the generalized symmetry condition permits both for device miniaturization and allows efficient realization at lower frequencies within a compact electronic circuit.
This innovative technique might enable scientists to override the prevalent difficulties in employing extensive networks of unobtrusive, long-lasting microsensors for monitoring large areas. In the ear of big data and Internet of things, these networks will be useful for smart cities, wireless health, and cyber-physical systems that actively gather and store large volumes of information for future analysis.
Development of wireless microsensors with high sensitivity is one of the major challenging issues for practical uses in bioimplants, wearable electronics, internet-of-things, and cyber-physical systems. While there has been continuous progress in miniature micro-machined sensors, the basics of telemetric readout technique remains essentially unchanged since its invention. This new telemetry approach will make possible the long-sought goal of successfully detecting tiny physical or chemical actuation from contactless microsensors.