Passive RF Injection Pen Sensing for Battery-Free Dose Tracking

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Solution Overview

Problem

Electronic injection devices face challenges with battery power depletion leading to device malfunction, incorrect dosages, or inability to operate, necessitating a power-free solution for reliable medicament delivery and data transmission.

Innovation Solution

The use of passive radio frequency (RF) signals for data transmission in injection devices, utilizing a resonating assembly with components like magnets, strain-sensitive resonators, and oscillators to modulate RF signals based on plunger rod position, eliminating the need for batteries and enabling efficient medicament volume measurement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If electronic components and batteries are used in injection devices for data transmission and usage detection, then functionality and data transmission capability are improved, but energy consumption increases and battery depletion leads to device malfunction

Engineering Contradiction:
Improvedevice operation reliabilityVSAvoidenergy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent removes the battery and active electronic components from the injection device. Instead of using active electronics for data transmission, the invention extracts only the essential passive RF identification functionality, allowing the device to communicate without its own power source. The RF module operates passively by harvesting energy from external interrogation signals.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The injection device uses passive RF technology where the device itself harvests the energy it needs from external interrogation signals. The RF module does not require an external battery but instead draws power from the interrogation signal received from external devices, making the system self-sufficient without traditional power sources.

Inventive Principle:
Principle #25Self-service

2Use of energy by moving object

If passive RF signals are used for data transmission, then energy consumption is reduced and battery-free operation is achieved, but communication range and signal strength may be limited

Engineering Contradiction:
Improveenergy consumptionVSAvoidcommunication range
Core Design Contradiction:
Use of energy by moving objectVSLength of moving object

Solution Approach 1:

The patent replaces active electronic transmission systems with passive RF modulation. Instead of using powered transmitters that consume battery energy, the system uses passive RF tags that modulate reflected interrogation signals. This substitution of active electronics with passive electromagnetic field interaction enables battery-free operation while maintaining communication capability through external device power.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables reliable, battery-free operation with long-range communication, ensuring accurate dosage delivery and data transmission, reducing environmental impact and operational complexity.

Implementation Method 1

a radio frequency (RF) antenna attached to the tubular side and configured to receive an interrogation signal from an external device

Methodology Applied
Scientific EffectElectromagnetic radiation: Electromagnetic Induction

Implementation Method 2

a resonating assembly configured to receive the interrogation signal from the RF antenna and to generate a modulated RF signal having a frequency associated with a position of the plunger rod

Methodology Applied
Scientific EffectResonance: Resonance

Data Source

PatentEP3727515B1Transmission of data associated with an injection device usage using passive RF modulation
Publication Date: 2026.03.18 SANOFI SA(FR)
  • EP3727515B1 patent drawingFigure 1A
  • EP3727515B1 patent drawingFigure 1B
  • EP3727515B1 patent drawingFigure 1C

AI summary

Implementations of the present disclosure are directed to an injection device including: a reservoir including a wall defining a proximal end, a distal end and a tubular side, a plunger rod configured to be movable within the reservoir in a direction from the distal end to the proximal end, a radio frequency (RF) antenna attached to the tubular side and configured to receive an interrogation signal from an external device, and a resonating assembly configured to receive the interrogation signal from the RF antenna and to generate a modulated RF signal having a frequency associated with a position of the plunger rod.