Wireless Sensor System for Lab-on-Chip Fluid Analysis
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Solution Overview
Problem
Current lab-on-chip devices face challenges in low-cost integration of CMOS/MEMS and microfluidics due to varying component sizes, leading to costly wafer-level integration and alignment issues, as well as difficulties in encapsulating sensors without damaging bond-wires and achieving a planar surface for microfluidic channel alignment.
Innovation Solution
A wireless sensor system is implemented, where a CMOS die is encapsulated within a recess of a substrate, allowing for contactless power and data transfer using wireless communication methods such as optoelectronic, near-field, or far-field techniques, eliminating the need for bond-wires and enabling precise alignment of microfluidic channels with sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wafer-level integration is used to integrate CMOS/MEMS and microfluidics, then integration is achieved, but manufacturing cost increases significantly due to component size mismatch
Solution Approach 1:
The device is divided into separate substrates: a first substrate containing the sensor and a second substrate containing the microfluidic channel. These substrates are integrated through fixed connection rather than wafer-level integration, allowing each to be optimized independently for cost and performance.
2Reliability
If encapsulation is performed using conventional methods, then sensor protection is achieved, but bond-wires are damaged due to mechanical stress from fluid viscosity and centrifugal forces
Solution Approach 1:
The bond-wires are completely removed from the system. Instead of wire-bonding the sensor to the substrate, the patent uses direct integration methods where the sensor is formed on the first substrate and connected through conductive structures embedded in the substrate, eliminating the vulnerable bond-wire component entirely.
3Reliability
If thick encapsulant is deposited to protect the sensor, then sensor protection is improved, but the top surface becomes non-planar causing alignment problems for microfluidic channels
Solution Approach 1:
The sensor is nested within a recess formed in the substrate. This recess accommodates the sensor and any encapsulant material, allowing the top surface of the substrate to remain planar and suitable for precise alignment with microfluidic channels while still providing protection for the sensor.
4Measurement precision
If alignment tolerance is tight to ensure proper sensor-channel matching, then sensing accuracy is improved, but assembly complexity and cost increase
Solution Approach 1:
The sensor position is predetermined during the formation of the first substrate, and the recess is positioned to receive the sensor at the correct location. This preliminary positioning eliminates the need for complex post-assembly alignment procedures, allowing standard alignment tolerances to be used while maintaining sensing accuracy.
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 reduces manufacturing costs, improves reliability, and simplifies assembly by avoiding parasitic wells and alignment complexities, allowing for robust and cost-effective mass production of lab-on-chip devices with improved sensor integration and microfluidic channel alignment.
Implementation Method 1
a wireless transmitter for transmitting data over a wireless data link; and a second substrate having formed thereon a wireless receiver for receiving data transmitted over said wireless link by said wireless transmitter
Data Source
AI summary
A device for sensing a property of a fluid comprising a first substrate having formed thereon a sensor configured in use to come into contact with a fluid in order to sense a property of the fluid, and a wireless transmitter for transmitting data over a wireless data link and a second substrate having formed thereon a wireless receiver for receiving data transmitted over said wireless link by said wireless transmitter. The first substrate is fixed to or within said second substrate. Additionally or alternatively, the device comprises a first substrate defining one or more microfluidic structures for receiving a fluid to be sensed and a second substrate comprising or having attached thereto a multiplicity of fluid sensors, the number of sensors being greater than the number of microfluidic structures. The second substrate is in contact with the first substrate such that at least one of the sensors is aligned with the or each microfluidic structure so as to provide an active sensor for the or each structure, and such that one or more of the sensors is or are not aligned with any microfluidic structure and is or are thereby redundant.