Printed PT Sensor Chip With Resistive Bridge for Low-Cost Home Testing
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Solution Overview
Problem
Existing point-of-care (POC) devices for measuring prothrombin time (PT/INR) are costly and inconsistent, making frequent at-home testing impractical for patients on chronic anticoagulation therapy, such as those with ventricular assist devices (VADs), which require frequent monitoring to avoid bleeding events.
Innovation Solution
A fully-printed sensor chip with conductive ink materials on a substrate, including electrodes and a resistive bridge, coupled with an impedance sensor and electronic controller, measures impedance changes in a blood sample to determine PT/INR using aerosol jet printing on flexible or rigid substrates, enabling low-cost, accurate, and portable testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional point-of-care devices are used for measuring prothrombin time, then measurement accuracy can be maintained, but device cost becomes prohibitively high and consistency deteriorates
Solution Approach 1:
The patent employs disposable sensor chips with printed electrodes that are inexpensive to manufacture using aerosol jet printing technology. These single-use chips eliminate the need for expensive, complex reusable devices while maintaining measurement accuracy through standardized printed circuit designs and consistent material properties.
Solution Approach 2:
The patent replaces complex mechanical and electronic assembly processes with aerosol jet printing, which deposits conductive materials directly onto substrate surfaces to form functional electrodes and circuits. This substitution of manufacturing methods significantly reduces device cost and complexity while maintaining measurement precision.
2Measurement precision
If traditional point-of-care devices are used for measuring prothrombin time, then measurement accuracy can be maintained, but measurement consistency across devices deteriorates
Solution Approach 1:
The patent standardizes critical measurement parameters including electrode geometry, spacing, and material composition through the aerosol jet printing process. This parameter control ensures that all sensor chips produce consistent baseline impedance values and respond uniformly to blood clotting events, improving inter-device reliability.
Solution Approach 2:
The patent creates a universal sensor chip design that can be mass-produced with identical electrical and physical characteristics. The standardized printed electrode patterns and substrate specifications ensure that any chip from the same production batch performs consistently, enabling reliable comparisons across multiple devices and users.
3Reliability
If frequent at-home testing is implemented, then patient monitoring effectiveness improves, but device portability and ease of use must be sufficient for home environments
Solution Approach 1:
The patent divides the monitoring system into a reusable handheld controller and disposable sensor chips. This segmentation allows the complex measurement electronics to be contained in a portable handheld device while the sensor chips remain simple, lightweight components that can be easily carried and replaced at home by patients.
Solution Approach 2:
The disposable sensor chips eliminate the need for complex calibration and maintenance procedures, making the device extremely easy to operate at home. Patients simply attach a new chip to the handheld device, perform the test, and discard the chip, enabling frequent monitoring without requiring technical expertise.
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 system provides accurate PT/INR measurements with standard deviation comparable to stationary systems, facilitating frequent, low-cost, and reliable at-home testing, potentially improving patient outcomes by early detection of derangements in clotting tendencies.
Implementation Method 1
an impedance of the blood sample is determined based on a measured impedance between the two contact pads
Implementation Method 2
The printing is performed on the surface of the substrate using aerosol jet printing
Implementation Method 3
The resistive bridge increases a baseline measurement to a value within a range that is measurable by lower-cost measurement equipment
Data Source
AI summary
A fully-printed sensor chip for measuring prothrombin time of a blood sample. The sensor chip includes a pair of electrodes and a pair of contact pads, each electrically coupled to a different one of the electrodes, printed on the surface of the substrate using conductive ink materials. When a blood sample is placed on the sample chip in contact with both electrodes, an impedance of the blood sample is determined based on a measured impedance between the two contact pads. As the blood sample clots, the impedance value changes and the prothrombin time for the blood sample is determined based on a measurement time of a maximum impedance value. A resistive bridge printed on the substrate surface between the contact pads increases a baseline measurement for the sensor chip to a value within a range that is measurable by lower-cost measurement equipment.