Moisture Sensor Pad for Vascular Access Bleeding Detection
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Solution Overview
Problem
Existing moisture detection devices for monitoring vascular access during extracorporeal blood treatment often suffer from false alarms due to perspiration, and they lack reliability in distinguishing between bleeding and other body fluids, posing a risk to patient safety.
Innovation Solution
A flexible, impermeable-to-liquid cover with a moisture sensor on top, allowing only larger amounts of fluid to reach the sensor, combined with a design that includes a recess for the cannula and a breaking line for easy handling, reduces false alarms and ensures reliable detection of bleeding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a moisture sensor is embedded in an absorbent pad placed on the puncture site, then moisture detection capability is improved, but false alarms occur due to inability to distinguish between bleeding and perspiration
Solution Approach 1:
The pad is designed with spatially differentiated properties: the first region (center) is permeable to allow blood to reach the sensor, while the second region (periphery) is impermeable to block perspiration. This local quality differentiation enables the sensor to detect only blood moisture without false alarms from perspiration.
Solution Approach 2:
The pad is segmented into functionally distinct regions: a central first region for blood detection and a peripheral second region for perspiration blocking. This segmentation allows different parts of the same device to perform different functions, resolving the contradiction between detection sensitivity and false alarm prevention.
2Reliability
If a hydrophobic filter with pores is used to block perspiration, then false alarms are reduced, but the device complexity increases due to multi-layer construction
Solution Approach 1:
Instead of using complex multi-layer hydrophobic filters throughout the entire pad, the invention applies the impermeable property only to the specific peripheral region where perspiration blocking is needed, while keeping the central region simple and permeable. This reduces overall device complexity while maintaining reliability.
3Measurement precision
If the moisture sensor is placed close to the puncture site for sensitive detection, then detection sensitivity is improved, but false alarms from perspiration increase
Solution Approach 1:
The sensor is positioned in the central first region which is permeable to blood, allowing high detection sensitivity. The surrounding peripheral second region is impermeable to perspiration, creating a protective zone that blocks harmful perspiration interference while maintaining close proximity for sensitive blood detection.
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
The solution effectively minimizes false alarms from perspiration while ensuring accurate detection of bleeding, enhancing patient safety by preventing unnecessary interruptions and ensuring proper vascular access monitoring.
Implementation Method 1
The humidity sensor is embedded between the top and bottom layers. It consists of a material layer on which a meandering conductor track is printed, the ends of which are designed as contacts. Moisture is detected by the change in resistance between the contacts of the conductor track.
Implementation Method 2
The adhesive layer is covered by a covering layer, for example a film or paper, which is removed before the cover is applied to the patient's skin.
Data Source
Figure 1
Figure 2~5
Figure 6~7B
AI summary
The invention relates to an apparatus (40) for detecting moisture, which is intended for the use in an apparatus (B) for monitoring an access to a patient for a device by means of which a fluid is conducted to and/or removed from a patient via a hose line, in particular for monitoring the vascular access during an extracorporeal blood treatment, wherein blood of a patient is removed from the patient via an arterial hose line (5), which has an arterial puncture cannula (6), and is conducted back to the patient via a venous hose line (7), which has a venous puncture cannula (8). The apparatus according to the invention for detecting moisture is designed as a pad (22) which is made of a flexible material and is to be applied onto the patient's skin and which comprises an upper side (22A) facing away from the patient's skin and a lower side (22B) facing the patient's skin. The pad (22) comprises an opening (23) for the passage of fluid, in particular blood, and a moisture sensor (28) having contact elements (28D, 28E) for the connection of the same. The moisture sensor (28) is capable of detecting blood flowing through the opening (23) to the surface of the pad (22). The apparatus according to the invention is characterized in that the lower side (22A) of the pad (22) is impervious to fluid.