Blister Pack Monitoring via Resistive Trace Merging
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Solution Overview
Problem
Existing electronic monitoring systems for blister packaging of medications require a large number of conductive traces, leading to increased costs and potential reliability issues due to the need for multiple inputs and close trace placement, which can result in accidental damage and false signaling of blister openings.
Innovation Solution
An analog approach using resistive traces connected in parallel with reference resistors, where all traces are formed at the same time from the same materials and under the same conditions, with the detection based on resistance ratios rather than actual resistor values, and utilizing adaptive algorithms and ratiometric voltage measurement for battery-powered operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If digital approaches with conductive traces are used to monitor each blister opening, then detection capability is achieved, but the number of traces and inputs increases leading to higher costs and reduced reliability
Solution Approach 1:
Multiple individual conductive traces are merged into a single continuous trace that meanders behind multiple blisters. The trace forms loops that pass behind each blister, creating multiple detection points along a single continuous path. This merging reduces the number of separate traces and electronic inputs from many individual traces to just one continuous trace with multiple monitoring zones.
Solution Approach 2:
A single continuous trace serves multiple functions: it monitors opening of multiple different blisters simultaneously, provides redundant detection paths, and acts as both a structural element and a sensing element. The trace is designed to be broken by opening any blister, making it a universal monitoring solution for all blisters on the card.
2Measurement precision
If multiple conductive traces are placed close together to monitor each blister, then individual blister detection is achieved, but accidental damage and false signaling increase
Solution Approach 1:
The single continuous trace is segmented into multiple functional zones or loops, each associated with a specific blister. Each loop or segment passes behind a particular blister, creating distinct detection zones along the continuous trace. This segmentation allows precise identification of which blister was opened while maintaining the physical integrity and spacing of the overall trace structure.
Solution Approach 2:
Instead of placing multiple traces close together in a two-dimensional plane (which risks accidental damage), the solution uses a single trace that extends in another dimension by meandering or looping behind each blister. This spatial reconfiguration distributes the trace material across a larger area, reducing local density and the risk of accidental damage while maintaining detection capability.
3Device complexity
If analog approach with resistive traces connected in parallel is used, then the number of traces is reduced, but detection complexity increases
Solution Approach 1:
The mechanical/digital approach of using separate conductive traces for each blister is replaced with an electrical/analog approach using resistive traces connected in parallel. The system measures the equivalent resistance of the parallel network, which changes as blisters are opened and traces are broken. This substitution simplifies the physical trace configuration while using electrical measurement principles to achieve detection.
Solution Approach 2:
A reference resistor is introduced as an intermediary element in the measurement circuit. The reference resistor provides a stable comparison value against which the variable resistance of the parallel trace network is measured. This intermediary enables accurate detection of resistance changes caused by trace breakage while compensating for variations in power supply voltage and environmental conditions.
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
This solution reduces the number of traces needed, decreases costs, enhances reliability by minimizing accidental breakage, and extends battery life through efficient power management, while maintaining accurate monitoring of blister openings.
Implementation Method 1
the detection based on resistance ratios rather than actual resistor values, and utilizing adaptive algorithms and ratiometric voltage measurement
Implementation Method 2
An analog approach using resistive traces connected in parallel with reference resistors
Data Source
AI summary
A system is provided for monitoring the removal of blister pack contents. An array of spatially-extended, electrically parallel breakable traces made from electrically resistive material is formed behind a corresponding array of blisters of a blister card. Then this array is connected in series with a reference resistor to form a voltage divider. All resistive traces are formed from the same materials in a single operation. Blister breakage is determined using changes in the ratio of the resistances of the array and the divider. A predictive algorithm is used to adjust the threshold resistance ratio change that signals blister breakage and voltage ratios are used to adjust for battery output changes over time. Breakage events and their time of occurrence are recorded in nonvolatile memory for later retrieval. Additional resistors can be used for activating the system and detecting tampering.