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Battery-less Long-Range LTE-M Water Leak Detector

Roshan Nepal, Brandon Brown, Shishangbo Yu, Roozbeh Abbasi, Norman Zhou, George Shaker

TL;DR

This paper tackles the challenge of autonomous water-leak monitoring without batteries or gateways by proposing a battery-free system that harvests energy from water-triggered electrochemical reactions and transmits alerts directly over LTE-M to the cloud. The architecture employs a dual-compartment electrochemical sensor to boost available voltage, a low-voltage ME2108 boost converter, a 1.5 F supercapacitor, and a TLV431-based comparator to gate power to a nRF9160 LTE-M modem, enabling self-powered wake-up and beaconing. Experimental validation demonstrates end-to-end operation from water exposure to cloud communication, with the system able to sustain multiple LTE-M transmissions on a single charge and avoid brownouts thanks to the energy buffer and gating strategy. The approach leverages 3GPP LTE-M and compatibility with non-terrestrial 5G networks, offering a maintenance-free, long-range monitoring solution suitable for remote or infrastructure-scarce deployments.

Abstract

This work presents a self powered water leak sensor that eliminates both batteries and local gateways. The design integrates a dual compartment electrochemical harvester, a low input boost converter with supercapacitor storage, and a comparator gated LTE-M radio built on the Nordic Thingy:91 platform. Laboratory tests confirm that the system can be awakened from a dormant state in the presence of water, harvest sufficient energy, and issue repeated cloud beacons using the water exposure as the power source. Beyond conventional LTE-M deployments, the system's compatibility with 3GPP standard cellular protocols paves the way for future connectivity via non terrestrial 5G networks, enabling coverage in infrastructure scarce regions.

Battery-less Long-Range LTE-M Water Leak Detector

TL;DR

This paper tackles the challenge of autonomous water-leak monitoring without batteries or gateways by proposing a battery-free system that harvests energy from water-triggered electrochemical reactions and transmits alerts directly over LTE-M to the cloud. The architecture employs a dual-compartment electrochemical sensor to boost available voltage, a low-voltage ME2108 boost converter, a 1.5 F supercapacitor, and a TLV431-based comparator to gate power to a nRF9160 LTE-M modem, enabling self-powered wake-up and beaconing. Experimental validation demonstrates end-to-end operation from water exposure to cloud communication, with the system able to sustain multiple LTE-M transmissions on a single charge and avoid brownouts thanks to the energy buffer and gating strategy. The approach leverages 3GPP LTE-M and compatibility with non-terrestrial 5G networks, offering a maintenance-free, long-range monitoring solution suitable for remote or infrastructure-scarce deployments.

Abstract

This work presents a self powered water leak sensor that eliminates both batteries and local gateways. The design integrates a dual compartment electrochemical harvester, a low input boost converter with supercapacitor storage, and a comparator gated LTE-M radio built on the Nordic Thingy:91 platform. Laboratory tests confirm that the system can be awakened from a dormant state in the presence of water, harvest sufficient energy, and issue repeated cloud beacons using the water exposure as the power source. Beyond conventional LTE-M deployments, the system's compatibility with 3GPP standard cellular protocols paves the way for future connectivity via non terrestrial 5G networks, enabling coverage in infrastructure scarce regions.
Paper Structure (4 sections, 5 figures)

This paper contains 4 sections, 5 figures.

Table of Contents

  1. Introduction
  2. System Architecture and Methodology
  3. Experimental Validation
  4. Conclusion

Figures (5)

  • Figure 1: CAD representation of the custom sensor enclosure: (a) Isometric view highlighting the dual-compartment layout for electrode and electrolyte placement; (b) Bottom view showing integrated inlet pathways designed to facilitate water ingress and initiate electrochemical energy generation.
  • Figure 2: OCV (left y-axis) and SCC (right y-axis) output of the sensor over time after water exposure.
  • Figure 3: Measured efficiency of the 5 V boost converter at 1.2 V input with varying output currents.
  • Figure 4: System architecture of the self-powered LTE-M system, where harvested energy powers the nRF9160 modem to transmit leak data to the cloud via MQTT.
  • Figure 5: Supercapacitor voltage profile showing comparator-based load control. The load activates at $V_{\text{on}} = 4.87~V$ and deactivates at $V_{\text{off}} = 3.67~V$, with periodic voltage dips marking successive beacon transmissions at 2-minute intervals.