Flexible Flow Governor for Medicinal Inhalers
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Solution Overview
Problem
Conventional pressurized metered dose inhalers (pMDIs) face challenges in delivering aerosolized medicaments effectively due to poor inhalation flow rate control and coordination between inhalation and dose release, leading to suboptimal drug deposition in the lungs, particularly for patients with respiratory diseases like asthma and COPD.
Innovation Solution
The development of a flow governor for medicinal inhalers that adjusts its geometry and resistance to air flow based on pressure drop, incorporating a tubular element with flexible walls that flex inwardly and an internal support structure to maintain a predetermined cross-sectional area, thereby regulating inhalation flow rates and reducing variability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional pMDI devices are used without flow control, then ease of operation is improved, but inhalation flow rate control deteriorates leading to suboptimal drug deposition
Solution Approach 1:
The flow governor dynamically changes the resistance parameter in response to pressure drop variations during inhalation. As pressure drop increases, the flexible wall deflects to reduce the flow passage cross-sectional area, thereby increasing resistance and limiting maximum flow rate. This automatic parameter adjustment maintains optimal inhalation flow rates without requiring complex electronic controls or spacers.
2Reliability
If breath-actuated triggering is implemented, then coordination between inhalation and dose release is improved, but inability to control inhalation flow rate deteriorates leading to excessive throat deposition
Solution Approach 1:
The flow governor modifies the flow resistance parameter dynamically based on real-time pressure drop conditions. The flexible wall deflects inward as pressure drop increases, automatically reducing the flow passage area and limiting maximum inhalation flow rate to the optimal range of 30-60 L/min, thereby preventing excessive throat deposition even when patients inhale vigorously.
Solution Approach 2:
The flow governor employs passive feedback through the flexible wall that responds to pressure drop variations. The wall deflection is directly proportional to the pressure drop, creating an automatic feedback mechanism that adjusts resistance without requiring electronic sensors or active control systems, thus maintaining simplicity while achieving flow rate control.
3Productivity
If high inspiratory flow rates are achieved, then productivity of drug delivery is improved, but drug deposition on the back of the throat increases leading to reduced lung penetration
Solution Approach 1:
The flow governor changes the resistance parameter in response to pressure drop, automatically limiting maximum flow rates to the optimal range. The flexible wall deflects to reduce passage area when pressure drop indicates high flow rates, preventing excessive throat deposition while maintaining sufficient drug delivery efficiency to the lungs.
4Object-generated harmful factors
If very low inspiratory flow rates are used, then throat deposition is reduced, but aerosolized medicament entrainment deteriorates leading to poor lung penetration
Solution Approach 1:
The flow governor maintains resistance within an optimal range that balances throat deposition prevention with adequate aerosol entrainment. By dynamically adjusting resistance through flexible wall deflection, it ensures flow rates remain high enough for proper aerosol pickup while low enough to prevent excessive throat deposition.
5Manufacturing precision
If fixed high resistance is added to control flow rate, then inhalation flow rate control is improved, but device complexity and patient effort increase
Solution Approach 1:
The flow governor uses a simple flexible wall structure that passively changes resistance based on pressure drop without requiring electronic components, motors, or complex mechanisms. The resistance adjustment is achieved through the natural elastic deflection of the flexible wall, maintaining device simplicity while achieving dynamic flow rate control.
Solution Approach 2:
The flow governor is self-regulating through the flexible wall's automatic response to pressure drop. The system adjusts its own resistance parameter based on operating conditions without external control, eliminating the need for electronic sensors, processors, or actuators, thus keeping the device simple and reliable.
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 enhances consistent drug deposition in the lungs by controlling inhalation flow rates, improving therapeutic efficacy and reducing the need for bulky spacer devices, while being suitable for a wide range of patients, including those with impaired lung function.
Implementation Method 1
The flow governor is adapted to change its geometry, and thereby its resistance to air flow, as a function of pressure drop between its inlet and its outlet
Implementation Method 2
a tubular element that defines at least a portion of an air flow path, the tubular element comprising at least one flexible wall configured to flex inwardly in response to an air flow in the air flow path
Data Source
AI summary
A flow governor for use in a medicinal inhaler. The flow governor can include (i) a tubular element that defines at least a portion of an air flow path, the tubular element comprising at least one flexible wall configured to flex inwardly in response to an air flow in the air flow path; and (ii) an internal support structure, located within the tubular element and configured to preserve at least a predetermined cross-sectional area of the air flow path within the tubular element when the at least one flexible wall of the tubular element flexes inwardly.