Electrochemical Sensor Chip Bulk Fabrication and Flip-Chip Integration
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Solution Overview
Problem
Current electrochemical sensors for measuring analyte concentrations in tear fluid, used for diagnosing and monitoring biological conditions, face challenges in efficient fabrication and integration with other electronics, particularly when mounted on the eye as a contact lens, due to the complexity of electrode fabrication and the need for compatible materials.
Innovation Solution
The development of an electrochemical sensor system where the sensor electrodes are fabricated on a common substrate, allowing for bulk production and isolation from other device electronics, enabling efficient flip-chip mounting into a body-mountable device like a contact lens, with a power harvesting and communication system integrated within the polymeric material, facilitating wireless data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If electrochemical sensors are fabricated using traditional methods with direct integration of electrodes and electronics, then functional integration is achieved, but fabrication complexity and manufacturing difficulty increase significantly
Solution Approach 1:
The device is divided into separate functional modules: the electrochemical sensor chip with electrodes is fabricated independently on a first substrate, while the electronics are integrated separately on a second substrate. These modules are then coupled together through wire bonds, allowing each to be manufactured using optimized processes without interfering with the other, thereby reducing overall fabrication complexity
Solution Approach 2:
A wire bond serves as an intermediary connection between the sensor chip and the electronics substrate. This intermediate coupling method allows for flexible integration of separately fabricated components, simplifying the manufacturing process by enabling independent optimization of sensor and electronics fabrication while maintaining functional integration
2Adaptability or versatility
If electrode fabrication is integrated with other device components, then functional integration is improved, but manufacturing precision and material compatibility requirements increase
Solution Approach 1:
The sensor chip and electronics are segmented into separate substrates that can be manufactured independently with their own optimized material stacks and fabrication processes. The sensor substrate can use materials and structures optimized for electrochemical sensing, while the electronics substrate can be optimized for electronic circuit fabrication, thereby maintaining high manufacturing precision for each component without compromise
3Adaptability or versatility
If sensors are produced individually, then customization is possible, but production efficiency and cost-effectiveness decrease
Solution Approach 1:
Multiple sensor electrodes are fabricated simultaneously on a common substrate in a bulk manufacturing process. The substrate is prepared with multiple electrode patterns, and all sensors are manufactured in parallel using the same fabrication steps. After fabrication, the substrate is diced into individual sensor chips, enabling high-volume production while maintaining the ability to customize sensor designs by modifying the common substrate pattern
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 efficient, cost-effective production of electrochemical sensors that can be seamlessly integrated into eye-mountable devices, providing accurate analyte concentration measurements while avoiding the limitations of traditional fabrication methods and ensuring biocompatibility.
Implementation Method 1
a positively charged electrode receives electrons from the analyte in an oxidation (or ionization) reaction where the analyte becomes more positively charged
Implementation Method 2
a negatively charged electrode donates electrons to the analyte in a reduction reaction where the analyte becomes more negatively charged
Implementation Method 3
Electrochemical amperometric sensors measure concentrations of an analyte by measuring currents caused by oxidation or reduction reactions of the analyte in the presence of a charged electrode
Implementation Method 4
For example, glucose oxidase can be fixed near the working electrode to react with glucose and release hydrogen peroxide
Implementation Method 5
hydrogen peroxide, which is then electrochemically detected by the working electrode to indicate the presence of glucose
Data Source
Figure 1
Figure 2A~2B
Figure 2C~2D
AI summary
An electrochemical sensor is disposed on a sensor substrate suitable for flip-chip mounting to another substrate. The electrochemical sensor can be fabricated in bulk by patterning sets of electrodes on a common substrate with vias that electrically couple each electrode to a conductive pad on the opposite side of the substrate. The substrate with electrodes thereon can then be diced and the individual electrochemical sensors can be flip-chip mounted in a body-mountable device in which the sensor can be used to obtain analyte concentrations. As a result, fabrication of the electrochemical sensor electrodes can be isolated from fabrication of the other electronics in the device, which can facilitate efficient fabrication of the sensor and allows for other electronics to be fabricated without restrictions associated with the electrode fabrication.