Implantable Device Orientation Calibration via Acceleration
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Solution Overview
Problem
Implantable medical devices (IMDs) experience orientation changes due to migration, rotation, or flipping, leading to inaccurate signal detection and inappropriate therapy, as existing calibration methods are often manual and not timely, increasing patient risk and medical costs.
Innovation Solution
A calibration circuit that receives acceleration information from the IMD and a reference device, determining a spatial relationship to correct for orientation changes, using a transformation matrix to calibrate subsequent acceleration data, enabling timely and automatic orientation adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual calibration methods are used for IMD orientation, then calibration can be performed, but the process is not timely and increases patient risk
Solution Approach 1:
The IMD performs automatic self-calibration by comparing acceleration data from its own accelerometer with reference acceleration data from a mobile device. The device independently determines the transformation matrix without requiring manual intervention, making the calibration process timely and reducing patient risk.
Solution Approach 2:
The calibration process is performed proactively by automatically detecting orientation changes and applying correction transformations before they affect therapy delivery. The system continuously monitors acceleration data and pre-computes transformation matrices to ensure accurate signal detection and appropriate therapy timing.
2Productivity
If IMD orientation changes are not corrected, then device operation continues, but signal detection becomes inaccurate leading to inappropriate therapy
Solution Approach 1:
The system changes the parameter representation of acceleration data by applying a transformation matrix that accounts for IMD orientation changes. The calibrated acceleration data is transformed from the IMD's coordinate system to the reference coordinate system, correcting signal characteristics such as amplitude, polarity, and timing to maintain detection accuracy.
Solution Approach 2:
The system continuously monitors acceleration data from both the IMD and reference device, compares the orientation, and automatically applies correction transformations when misalignment is detected. This closed-loop feedback mechanism ensures signal detection accuracy is maintained despite orientation changes, preventing inappropriate therapy delivery.
3Reliability
If automatic calibration is implemented, then orientation changes are detected timely, but device complexity increases
Solution Approach 1:
The mobile device serves multiple functions: it acts as both a reference accelerometer for orientation calibration and a wireless communication device for data transmission. By utilizing the existing sensors and communication capabilities of the mobile device, the system avoids adding dedicated calibration hardware to the IMD, thereby reducing device complexity while maintaining reliable orientation 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
This approach allows for timely detection of IMD orientation changes, reducing patient risk, lowering medical costs, and improving care provider efficiency by automating the calibration process, ensuring accurate signal detection and appropriate therapy.
Implementation Method 1
an accelerometer sensor to detect patient posture or physical activity
Data Source
AI summary
Systems and methods for calibrating an orientation of an implantable device in a patient is described. An exemplary system includes a calibration circuit that can receive acceleration information sensed from an implantable medical device (IMD) implanted in a patient, and receive reference acceleration information sensed from a reference device associated with the patient. The acceleration information and the reference acceleration information are acquired when the patient assumes a first posture or in a first position. The calibration circuit determines a spatial relationship between an orientation of the IMD and a reference orientation of the reference device using the received acceleration information and the received reference acceleration information, and calibrate subsequent acceleration information sensed from the IMD using the determined spatial relationship to correct for the orientation of the IMD.