Week 4 - Bio-MEMS for Breast Cancer Diagnosis
Here are the keynotes summarizing the module on fabricating and utilizing a Bio-MEMS chip for
breast cancer diagnosis:
Portable Cancer Diagnostic Tool Using a Disposable
MEMS-Based Biochip
### Overview of Bio-MEMS Chip Fabrication
- **Definition**: Bio-MEMS refers to microelectromechanical systems used for biological
applications.
- **Components**: The chip consists of:
- Heater
- Insulator
- Piezoresistive sensor
- Gold pad
- SU-8 pillars
- Diaphragm (fabricated using bulk micromachining)
### Mechanical Casing
- **3D Printing**: The mechanical casing for the chip is fabricated using 3D printing.
- **Module Design**: The chip is housed in a designed module to facilitate tissue interaction.
### Functionality of the Chip
1. **Press Fit Contacts**: Allows easy loading/unloading of the chip into the casing.
2. **Micro Manipulator**: Utilizes a piezoactuator or micro manipulator to apply controlled
pressure to the tissue.
3. **Tissue Loading**: Tissue is loaded through a funnel and contacts the chip for
measurements.
### Measurement Techniques
- **Mechanical Properties**:
- Elasticity or stiffness measured by applying force and assessing response.
- **Electrical Properties**:
- Resistance is measured by applying a voltage across the tissue.
- **Thermal Properties**:
- Thermal conductivity is assessed by measuring temperature differences across the tissue.
### Applications in Breast Cancer Diagnosis
,- **Tissue Types**: Can analyze tissues from benign to various stages of cancer (e.g., invasive
ductal carcinoma).
- **Correlation with Biomarkers**: Findings can be correlated with standard biomarkers to
improve diagnostic accuracy.
### Research Findings
- **Property Changes**: Studies indicate distinct changes in mechanical, electrical, and thermal
properties between normal and cancerous tissues.
- **Morphological Differences**: SEM images show that cancerous tissues are rougher,
influencing resistance and thermal conductivity.
### Future Directions
- **Broader Applications**: The technology can be adapted for various tissue-related cancers
(e.g., oral, prostate).
- **Next Module Focus**: Future discussions will include simplifying the design for measuring
only mechanical properties, using a piezoresistive microcantilever.
### Conclusion
- The module highlights the potential of MEMS-based biochips in understanding and diagnosing
breast cancer through mechanical, electrical, and thermal property measurements of tissue
samples.
Mechanical Phenotyping of Breast Cancer using MEMS
Certainly! Here are key notes summarizing the module on mechanical phenotyping of breast
cancer using piezoresistive microcantilevers:
### Overview
- **Objective**: Differentiate between benign and cancerous breast tissues through mechanical
phenotyping.
- **Method**: Utilize a piezoresistive microcantilever to probe tissue mechanical properties.
### Microcantilever Design
- **Components**:
- Piezoresistive microcantilever with SU-8 tip.
- Embedded piezoresistor for resistance measurement.
- Contact pads for electrical connections.
### Microcantilever Mechanics
- **Function**:
- Cantilever is pressed against breast tissue.
- Bending of cantilever depends on tissue stiffness:
- Higher stiffness → more bending.
, - Lower stiffness → less bending.
- **Measurement**: Change in resistance of piezoresistor correlates to tissue stiffness.
### Fabrication Process
1. **Start with SOI Wafer**:
- Silicon on insulator (SOI) substrate.
2. **Thermal Oxidation**:
- Grow silicon dioxide layer.
3. **Window Creation**:
- Use photolithography to open windows for boron doping.
4. **Boron Diffusion**:
- Introduce boron to form piezoresistor.
5. **Additional Oxidation**:
- Grow more silicon dioxide.
6. **Contact Pad Creation**:
- Open regions for boron contacts and gold pads.
7. **Silicon Nitride Deposition**:
- Release stress in the wafer.
8. **Etching**:
- Etch silicon and silicon dioxide to define structures.
9. **SU-8 Tip Formation**:
- Spin coat and pattern SU-8.
10. **Backside Etching**:
- Use deep reactive ion etching (DRIE) for final chip realization.
### Experimental Setup
- **Equipment**:
- Micro manipulator (MP-285) with XY-stage.
- Inverted microscope with CCD camera and light source.
- **Procedure**:
- Position tissue microarray on glass slide.
- Indent tissue using piezoresistive microcantilever.
- Measure resistance changes to infer tissue stiffness.
### Tissue Analysis
- **Types of Tissues**:
- Different regions: benign epithelial, cancer epithelial, benign stromal, etc.
- **Outcome**: Ability to differentiate normal and cancerous tissues based on mechanical
properties.
### Future Directions
- Upcoming modules will discuss results and methodologies for demarcating between tissue
types based on mechanical phenotyping.
, ### Conclusion
- The piezoresistive microcantilever serves as a crucial tool for understanding tissue mechanics,
potentially aiding in early cancer detection and differentiation.
Electrical characterization of Breast Tissue Cores
Sure! Here’s a condensed set of key points based on your lecture:
### Understanding Tissue Properties Using Electrical Modality
1. **Introduction to Tissue Properties**:
- Importance of understanding electrical, mechanical, and thermal properties of tissues.
- Use of biochips and sensors to study these properties.
2. **Piezoresistive Microcantilever**:
- Device used to measure tissue elasticity and stiffness.
- Comparison of elasticity between normal and cancerous tissues:
- Epithelial region: Normal ~40 kPa vs. Cancer ~15 kPa.
- Stromal region: Normal ~80 kPa vs. Cancer ~20 kPa.
- Elasticity measurement helps differentiate between normal and cancerous tissues.
3. **Flexible Sensors**:
- Designed to understand both electrical and mechanical properties of tissues.
- Focus on fabricating a sensor with interdigitated electrodes.
4. **Interdigitated Electrode Sensors**:
- Constructed on oxidized silicon wafers with SU-8 wells.
- Each electrode has 10 µm width and spacing.
- Impedance/resistance of tissues can be measured when placed on electrodes.
5. **Functionality of the Sensor**:
- Normal and cancerous tissues exhibit different resistances.
- Sensor design prevents fluid spillage during tissue measurement (PBS solution contained in
SU-8 well).
6. **Fabrication Process**:
- Two-mask process to create interdigitated electrodes:
- Spin-coating, lithography, etching of metal (chrome/gold).
- SU-8 spin-coating for the well structure.
- Hard baking and developing to finalize the sensor design.
7. **Measuring Impedance**:
- Importance of impedance over resistance due to additional capacitance effects.
Here are the keynotes summarizing the module on fabricating and utilizing a Bio-MEMS chip for
breast cancer diagnosis:
Portable Cancer Diagnostic Tool Using a Disposable
MEMS-Based Biochip
### Overview of Bio-MEMS Chip Fabrication
- **Definition**: Bio-MEMS refers to microelectromechanical systems used for biological
applications.
- **Components**: The chip consists of:
- Heater
- Insulator
- Piezoresistive sensor
- Gold pad
- SU-8 pillars
- Diaphragm (fabricated using bulk micromachining)
### Mechanical Casing
- **3D Printing**: The mechanical casing for the chip is fabricated using 3D printing.
- **Module Design**: The chip is housed in a designed module to facilitate tissue interaction.
### Functionality of the Chip
1. **Press Fit Contacts**: Allows easy loading/unloading of the chip into the casing.
2. **Micro Manipulator**: Utilizes a piezoactuator or micro manipulator to apply controlled
pressure to the tissue.
3. **Tissue Loading**: Tissue is loaded through a funnel and contacts the chip for
measurements.
### Measurement Techniques
- **Mechanical Properties**:
- Elasticity or stiffness measured by applying force and assessing response.
- **Electrical Properties**:
- Resistance is measured by applying a voltage across the tissue.
- **Thermal Properties**:
- Thermal conductivity is assessed by measuring temperature differences across the tissue.
### Applications in Breast Cancer Diagnosis
,- **Tissue Types**: Can analyze tissues from benign to various stages of cancer (e.g., invasive
ductal carcinoma).
- **Correlation with Biomarkers**: Findings can be correlated with standard biomarkers to
improve diagnostic accuracy.
### Research Findings
- **Property Changes**: Studies indicate distinct changes in mechanical, electrical, and thermal
properties between normal and cancerous tissues.
- **Morphological Differences**: SEM images show that cancerous tissues are rougher,
influencing resistance and thermal conductivity.
### Future Directions
- **Broader Applications**: The technology can be adapted for various tissue-related cancers
(e.g., oral, prostate).
- **Next Module Focus**: Future discussions will include simplifying the design for measuring
only mechanical properties, using a piezoresistive microcantilever.
### Conclusion
- The module highlights the potential of MEMS-based biochips in understanding and diagnosing
breast cancer through mechanical, electrical, and thermal property measurements of tissue
samples.
Mechanical Phenotyping of Breast Cancer using MEMS
Certainly! Here are key notes summarizing the module on mechanical phenotyping of breast
cancer using piezoresistive microcantilevers:
### Overview
- **Objective**: Differentiate between benign and cancerous breast tissues through mechanical
phenotyping.
- **Method**: Utilize a piezoresistive microcantilever to probe tissue mechanical properties.
### Microcantilever Design
- **Components**:
- Piezoresistive microcantilever with SU-8 tip.
- Embedded piezoresistor for resistance measurement.
- Contact pads for electrical connections.
### Microcantilever Mechanics
- **Function**:
- Cantilever is pressed against breast tissue.
- Bending of cantilever depends on tissue stiffness:
- Higher stiffness → more bending.
, - Lower stiffness → less bending.
- **Measurement**: Change in resistance of piezoresistor correlates to tissue stiffness.
### Fabrication Process
1. **Start with SOI Wafer**:
- Silicon on insulator (SOI) substrate.
2. **Thermal Oxidation**:
- Grow silicon dioxide layer.
3. **Window Creation**:
- Use photolithography to open windows for boron doping.
4. **Boron Diffusion**:
- Introduce boron to form piezoresistor.
5. **Additional Oxidation**:
- Grow more silicon dioxide.
6. **Contact Pad Creation**:
- Open regions for boron contacts and gold pads.
7. **Silicon Nitride Deposition**:
- Release stress in the wafer.
8. **Etching**:
- Etch silicon and silicon dioxide to define structures.
9. **SU-8 Tip Formation**:
- Spin coat and pattern SU-8.
10. **Backside Etching**:
- Use deep reactive ion etching (DRIE) for final chip realization.
### Experimental Setup
- **Equipment**:
- Micro manipulator (MP-285) with XY-stage.
- Inverted microscope with CCD camera and light source.
- **Procedure**:
- Position tissue microarray on glass slide.
- Indent tissue using piezoresistive microcantilever.
- Measure resistance changes to infer tissue stiffness.
### Tissue Analysis
- **Types of Tissues**:
- Different regions: benign epithelial, cancer epithelial, benign stromal, etc.
- **Outcome**: Ability to differentiate normal and cancerous tissues based on mechanical
properties.
### Future Directions
- Upcoming modules will discuss results and methodologies for demarcating between tissue
types based on mechanical phenotyping.
, ### Conclusion
- The piezoresistive microcantilever serves as a crucial tool for understanding tissue mechanics,
potentially aiding in early cancer detection and differentiation.
Electrical characterization of Breast Tissue Cores
Sure! Here’s a condensed set of key points based on your lecture:
### Understanding Tissue Properties Using Electrical Modality
1. **Introduction to Tissue Properties**:
- Importance of understanding electrical, mechanical, and thermal properties of tissues.
- Use of biochips and sensors to study these properties.
2. **Piezoresistive Microcantilever**:
- Device used to measure tissue elasticity and stiffness.
- Comparison of elasticity between normal and cancerous tissues:
- Epithelial region: Normal ~40 kPa vs. Cancer ~15 kPa.
- Stromal region: Normal ~80 kPa vs. Cancer ~20 kPa.
- Elasticity measurement helps differentiate between normal and cancerous tissues.
3. **Flexible Sensors**:
- Designed to understand both electrical and mechanical properties of tissues.
- Focus on fabricating a sensor with interdigitated electrodes.
4. **Interdigitated Electrode Sensors**:
- Constructed on oxidized silicon wafers with SU-8 wells.
- Each electrode has 10 µm width and spacing.
- Impedance/resistance of tissues can be measured when placed on electrodes.
5. **Functionality of the Sensor**:
- Normal and cancerous tissues exhibit different resistances.
- Sensor design prevents fluid spillage during tissue measurement (PBS solution contained in
SU-8 well).
6. **Fabrication Process**:
- Two-mask process to create interdigitated electrodes:
- Spin-coating, lithography, etching of metal (chrome/gold).
- SU-8 spin-coating for the well structure.
- Hard baking and developing to finalize the sensor design.
7. **Measuring Impedance**:
- Importance of impedance over resistance due to additional capacitance effects.
