Finger Cuff Extended Fixed Shell Reduces Movement
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Solution Overview
Problem
Conventional finger cuffs are prone to noise interference due to patient finger movement, limiting their use to sedated patients and compromising blood pressure measurement accuracy in awake individuals.
Innovation Solution
A finger cuff design featuring an extended fixed shell with a finger cavity that surrounds a large portion of the finger, including the middle knuckle, and a support member to reduce finger movement, combined with a bladder and LED-PD pair for accurate blood pressure measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a flexible band with conventional securing means (Velcro) is used to wrap around the finger, then the finger cuff can be easily applied and removed, but finger movement occurs causing noise in blood pressure measurements
Solution Approach 1:
The finger cuff is divided into a flexible band portion for easy application and a rigid shell portion for stability. The flexible band wraps around the finger and secures the rigid shell in place, combining the ease of application with the stability needed to prevent finger movement during measurement.
Solution Approach 2:
The finger cuff combines flexible material (for the band) with rigid material (for the shell) to create a composite structure. This allows the cuff to be easily applied like a flexible band while the rigid shell portion prevents finger movement and maintains measurement accuracy.
2Measurement precision
If a rigid shell structure is used to prevent finger movement, then measurement accuracy improves, but the device becomes more complex and difficult to apply
Solution Approach 1:
The cuff is segmented into simple functional components: a flexible band for application and a rigid shell for stability. This segmentation maintains measurement accuracy while keeping the overall device simple and easy to apply.
Solution Approach 2:
Rigidity is applied locally only where needed (in the shell portion that contacts the finger) rather than making the entire cuff rigid. The flexible band remains soft and compliant for easy application, while the localized rigid shell provides the necessary stability for accurate measurement.
3Device complexity
If the finger cuff surrounds only the distal phalanx, then the device remains simple, but relative movement between middle phalanx and proximal phalanx occurs causing measurement noise
Solution Approach 1:
The rigid shell extends along the longitudinal dimension of the finger to include the middle knuckle, rather than only surrounding the distal phalanx. This extended coverage in the longitudinal dimension prevents relative movement between phalanges while maintaining overall device simplicity.
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 design significantly reduces finger movement, enhancing the accuracy of blood pressure measurements and allowing for use with awake patients in various settings, such as emergency rooms and standard hospital rooms.
Implementation Method 1
The infrared light may be sent through the finger in which a finger artery is present. The infrared sensor picks up the infrared light and the amount of infrared light registered by the sensor may be inversely proportional to the artery diameter and indicative of the pressure in the artery.
Data Source
AI summary
Disclosed is finger cuff that is connectable to a patient's finger to be used in measuring the patient's blood pressure by a blood pressure measurement system. The finger cuff may comprise a fixed shell and a bladder. The fixed shell may have a finger cavity, in which the finger cavity of the fixed shell may be placed around a patient's finger to surround a large portion of the patient's finger including the middle knuckle to reduce finger movement, and in particular, to reduce relative movement between the middle phalanx and the proximal phalanx. Further, the fixed shell includes a support member that extends away from the finger cavity to abut against the underside of the patient's hand to reduce bending of the finger relative to the hand.