A chip-less and battery-less subharmonic tag for wireless sensing with parametrically enhanced sensitivity and dynamic range

Abstract

Massive deployments of wireless sensor nodes (WSNs) that continuously detect physical, biological or chemical parameters are needed to truly benefit from the unprecedented possibilities opened by the Internet-of-Things (IoT). Just recently, new sensors with higher sensitivities have been demonstrated by leveraging advanced on-chip designs and microfabrication processes. Yet, WSNs using such sensors require energy to transmit the sensed information. Consequently, they either contain batteries that need to be periodically replaced or energy harvesting circuits whose low efficiencies prevent a frequent and continuous sensing and impact the maximum range of communication. Here, we report a new chip-less and battery-less tag-based WSN that fundamentally breaks any previous paradigm. This WSN, formed by off-the-shelf lumped components on a printed substrate, can sense and transmit information without any need of supplied or harvested DC power, while enabling full-duplex transceiver designs for interrogating nodes rendering them immune to their own self-interference. Also, even though the reported WSN does not require any advanced and expensive manufacturing, its unique parametric dynamical behavior enables extraordinary sensitivities and dynamic ranges that can even surpass those achieved by on-chip sensors. The operation and performance of the first implementation of this new WSN are reported. This device operates in the Ultra-High-Frequency range and is capable to passively and continuously detect temperature changes remotely from an interrogating node.

Ising Dynamics for Programmable Threshold Sensing in Wireless Devices

“…Finally, we evaluated the resilience of the preferred coupling state to fluctuations in the input power that may occur due to multipath, a feature that makes any prior threshold-sensing device exploiting bifurcations unusable 18,19 . This was done through a wired experiment in which the two antennas were disconnected, and the SPIN's input and output ports were connected to a 50 Ω signal generator and to a 50 Ω oscilloscope, respectively.…”

“…This constraint heavily limits their usability in widespread sensor deployments 13 . As a result, there has been increased attention into the adoption of passive wireless sensor devices, namely passive tags (or nodes), to implement threshold sensing [14][15][16][17][18][19][20] .…”

“…Only recently, passive tags exploiting nonlinear processes have been proposed 18,19 to overcome the limited signal processing functionalities of linear passive tags and enable an autonomous implementation of threshold sensing. In these nonlinear tags, PoI violations activate an internal oscillation through a subcritical bifurcation, effectively triggering an alarm in the RF spectrum 18 .…”

Frequency Domain Acoustic-Based Subharmonic Tags for Far-Field Identification

“…In fact, in such operational scenario, the output signal of HTs is largely attenuated by any surrounding objects [28], differently from the SubHTs' output signal that is characterized by a much lower frequency. Also, by exploiting the non-Hermitian dynamics of parametric systems operating in the proximity of exceptional points (EPs [25]), the SubHTs used for remote sensing can achieve boosted sensitivities and dynamic ranges with respect to any other PTs [21]. The same dynamics have also recently enabled a threshold sensing functionality, equipped with a dynamic memory capability, without requiring any power-hungry memory devices [22].…”

“…For instance, several RF circulators [15]- [17], filters [18], [19] and isolators [20] have been developed, based on the unique dynamics triggered by the periodic modulation or switching of solid state capacitors. Just recently, our group has exploited similar dynamics to generate a new class of PTs dubbed as Subharmonic Tags (SubHTs [21]- [24] ). Sub-HTs permit to passively sense any parameter-of-interest (PoI) with dynamically boosted sensitivity and dynamic ranges.…”