Resonant Sensor Uniform Mass Sensitivity
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Solution Overview
Problem
Current microfabricated resonant mass sensors have spatially non-uniform mass sensitivity, making them less practical for measuring the mass of single or few target entities, as the mass sensitivity varies significantly across the cantilever beam structure, reducing their effectiveness in accurately determining cell mass and growth rate.
Innovation Solution
A microfabricated resonant sensor with a suspended platform supported by three or more tethers, exhibiting uniform vibration amplitude across the measuring surface, which maintains higher mass sensitivity regardless of the entity's position, achieved through a unique design with a folded geometry and materials like semiconductors, metals, and piezoelectric materials, allowing for precise measurement of cell mass and growth rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a cantilever beam structure is used for miniaturization, then mass sensitivity is improved, but spatial uniformity of mass sensitivity deteriorates
Solution Approach 1:
The sensor structure is divided into multiple identical cantilever beams (typically three or more) arranged in an array. Each cantilever is segmented into a uniform section and a tip section, with the uniform section providing consistent mass sensitivity across its length. This segmentation allows the sensor to achieve high mass sensitivity while maintaining spatial uniformity through the repeated modular structure.
Solution Approach 2:
Different sections of the cantilever beam are designed with different geometric properties to serve different functions. The uniform section has constant cross-section for consistent mass sensitivity, while the tip section may have varying geometry for enhanced sensitivity or functional purposes. This local differentiation resolves the contradiction by optimizing each region for its specific role.
2Measurement precision
If mass attachment is limited to the cantilever tip, then mass sensitivity is improved, but device complexity and ease of operation deteriorate
Solution Approach 1:
The uniform section of each cantilever beam serves multiple functions: it provides the primary mass sensitivity for detection, acts as a support structure, and serves as a valid attachment site for target masses. This multi-functionality eliminates the need to restrict attachment to the tip, making the sensor more versatile and easier to use while maintaining measurement precision.
Solution Approach 2:
The sensor array extends the attachment space from a single-point tip location to a two-dimensional uniform section area. This dimensional expansion allows target entities to be attached at multiple locations along the cantilever length, providing operational flexibility while the array configuration maintains overall measurement precision through redundant sensing elements.
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 sensor provides uniform mass sensitivity, enabling accurate measurement of cell mass and growth rate with minimal variation, overcoming the limitations of traditional cantilever beam sensors by maintaining high sensitivity across the platform, facilitating precise biological and chemical sensing.
Implementation Method 1
MEMS-based resonant mass sensors have been extensively studied as biological and chemical sensors. These sensors measure a shift in the resonance frequency of the structure before and after the target attachment, where the shift can be used to calculate the mass of the target entity.
Implementation Method 2
a piezoelectric material, allowing for precise measurement of cell mass and growth rate
Data Source
AI summary
Provided herein are sensors and methods for determining properties of single cells, such as cell mass. Sensors disclosed herein include resonant sensors having a suspended platform designed to exhibit a uniform vibration amplitude. Methods are also disclosed for measuring changes in cell mass, changes in cell number, changes in cell viscosity and changes in cell elasticity.