Optimizing Wireless Sensors in Industrial IoT

An Electrical Engineering Perspective

Wireless sensors are the backbone of Industrial IoT (IIoT), enabling real-time monitoring of machinery, environmental conditions, and asset tracking in factory settings. However, their performance depends heavily on overcoming specific electrical challenges tied to power delivery in harsh industrial environments. This blog post explores these challenges and how they can be addressed with a focus on electrical properties and system design—tailored for electrical engineers working on IIoT applications.

Electrical Challenges for Wireless Sensors in IIoT

Wireless sensors in industrial settings operate with a distinct electrical profile:

• Low-Power Sleep Mode: Drawing microamps while idle.

• High-Power Active Mode: Requiring short bursts of current (e.g., 50–500 mA for 10–100 ms) to measure and transmit data via protocols like LoRaWAN or Zigbee.

These operational demands introduce several electrical hurdles:

• Frequent Cycling: Sensors may activate thousands of times daily, necessitating a power source that can endure repeated charge-discharge cycles without degradation.

• Rapid Energy Delivery: High-current bursts must be supplied quickly to support data transmission, a task that requires low internal resistance.

• Wide Temperature Range: Industrial environments (-40°C to 85°C) demand stable performance across extreme conditions, where traditional power sources often falter.

• Maintenance Constraints: Sensors in remote or hazardous locations (e.g., rotating machinery or chemical plants) need power solutions that minimize or eliminate the need for manual intervention.

Addressing these challenges requires a power source optimized for high power density, rapid energy delivery, and durability—key electrical traits that enhance IIoT reliability.

Circuit Integration and Design Considerations

Designing an effective power system for IIoT wireless sensors involves several electrical engineering principles:

• Voltage Management: A stable output (e.g., 3.3 V) is critical for sensor electronics, often requiring a DC-DC boost converter (e.g., TI BQ25570 or LTC3105) to regulate voltage efficiently during discharge.

• Energy Requirements: The power source must meet the energy needs per transmission cycle. For example, a sensor consuming 10 mJ per burst (with an initial voltage of 3.5 V dropping to 1.5 V) requires careful sizing to ensure sufficient capacity.

• Low Leakage: With sensors spending most of their time in sleep mode, the power source should have minimal leakage current (e.g., 1–10 µA) to preserve energy, aligning with low-power MCUs like the STM32L0 series (<1 µA in sleep).

• Power Delivery Efficiency: Low equivalent series resistance (ESR, e.g., 10–100 mΩ) is essential to minimize voltage drops during high-current pulses (e.g., a 100 mA pulse results in just 1–10 mV sag).

• Hybrid Configurations: Combining the power source with energy harvesting (e.g., solar, vibration, or thermal) can create self-sustaining nodes, leveraging rapid charging to capitalize on intermittent energy inputs.

Practical Industrial Applications

Here’s how these electrical principles translate into real-world IIoT solutions:

1. Vibration Monitoring on CNC Machines

   • Setup: Powers a triaxial accelerometer and BLE module.

   • Operation: Delivers 100 mA for 20 ms bursts, charged by a 5 mW piezoelectric harvester.

   • Benefit: Ensures reliable operation in high-vibration environments without frequent maintenance.

2. Temperature Sensing in Hazardous Areas

   • Setup: Drives a PT100 sensor with LoRaWAN in a chemical reactor.

   • Operation: Supplies 500 mA bursts hourly, charged by a 50 mW thermal gradient.

   • Benefit: Maintains performance at 80°C in hard-to-access zones.

3. Asset Tracking in Warehouses

   • Setup: Powers a BLE beacon on a pallet.

   • Operation: Provides 50 ms pings every minute, charged by 2 mW ambient RF.

   • Benefit: Enables scalable, maintenance-free tracking across thousands of nodes.

Synergy with Energy Harvesting

Pairing the power system with energy harvesting enhances autonomy:

• Sources: Piezoelectric (5–20 mW from vibration), thermoelectric (10–100 mW from heat), or indoor solar (10–50 mW).

• Advantage: Rapid charging from low, intermittent inputs supports continuous operation without external power.

• Example: A 10 mW thermoelectric generator can sustain 50 daily sensor cycles, achieving full independence.

The electrical demands of wireless sensors in IIoT—frequent cycling, rapid energy delivery, temperature resilience, and minimal maintenance—require a power solution tailored for industrial reliability. By leveraging high power density, low ESR, and compatibility with energy harvesting, engineers can design sensor networks that are both efficient and sustainable.

For those looking to implement such solutions, Volfpack offers tailored options to meet your IIoT needs. Contact us at charliekaru@volfpackenergy.com or visit volfpackenergy.com to discuss how we can support your next project.