Programmable Multiwavelength Radio Frequency Spectrometry of Chemophysical Environments through an Adaptable Network of Flexible and Environmentally Responsive, Passive Wireless Elements

Abstract

Readout of multiparametric environmental signals typically uses discrete sensing formats that individually require unique signal conditioning circuitry and/or processing pathways. Here, adaptable sensor networks composed exclusively of passive material architectures that enable spectrometric comonitoring of chemical or physical environmental signals are proposed. Herein, a single radio frequency (RF) reader wirelessly interacts first with an intermediate wireless relay coil—this is tunable in length and can be designed to conform around surfaces. This relay (that is fused on textiles or surfaces) is then wirelessly coupled to arrays of passive RF sensors with individually programmable flexibility/reactivity to environmental signals. Multiple chemical and physical signals can then be monitored within the single spectral readout of a wearable reader. This technique can probe over tunable length scales, and is robust to mechanical disturbances that limit present techniques. As a proof of concept, this approach is used to comonitor chemophysical metrics such as nutrients, temperature, pressure, pH, and more on the skin or in utensils with a single readout. This technique may form a cornerstone of zero‐microelectronic sensor networks.

Rapid and on-site wireless immunoassay of respiratory virus aerosols via hydrogel-modulated resonators

“…8a ). The flexible IR coils facilitate the propagation of electromagnetic field to individual sensors along its pathlength or through designed inductive terminals 28 , enhancing the mechanical robustness of the network and stabilizing the multiplexed RF readout when it undergoes misalignment or deformation. The read coil, on the other hand, is a one-port planar coil connected to the portable vector network analyzer (VNA), which enables electromagnetic field emission and return loss (S 11 ) probing.…”

“…To handle this misalignment disturbance, ImmHR sensors are fixed on flexible IR coils that magnetically couple to the read coil (Supplementary Fig. 16a–c ), which helps stabilize the spectral readout during misalignment between the readout coil and the network 28 . The adoption of IR coils is simple to maintain due to the flexible nature of the IR.…”

“…Particularly, radio frequency (RF) resonators are featured with delicate inductance/capacitance structures which can be modulated by mechanical or dielectric variations, thus providing ideal transducers to exploit the responsiveness of hydrogel metamaterials 23 – 25 . The wireless readout and compatibility with wearable integration also allow for miniaturization and in situ signal recording, which make RF sensors suitable for advanced healthcare monitoring 26 – 28 .…”

All‐MXene‐Printed RF Resonators as Wireless Plant Wearable Sensors for In Situ Ethylene Detection

“…To measure the resonator wirelessly, we adopted PCB‐based planar readout coil that is generally used in RF sensors. [ 55 ] The readout coil is connected to the vector network analyzer by SMA interface. The portable VNA3000 enables electromagnetic parameter detection of the resonators from 1 MHZ to 3 GHz, which is then analyzed and displayed on a Java software (Figure S19, Supporting Information).…”

Broadside‐Coupled Split Ring Resonators as a Model Construct for Passive Wireless Sensing

“…Such weaknesses are being addressed by emerging techniques that modify sensors and their accompanying readout strategy. For example, sensors may be integrated into more complex structural relay networks that either significantly improve spectral stability, [20,21] or augment readout by enabling long-distance interrogation. [22] System sensitivity may be improved using advanced electromagnetic strategies whereby sensing circuits are tuned to exceptional points of degeneracy (EPD)-this may be through circuits exhibiting parity-time (PT) symmetry, or EPD induced via time modulation.…”