Microengineering Devices Lecture 03

Introduction to Microengineering Devices

• Focus on fabrication techniques for MEMS-based sensors relevant in medical diagnostics.
• Importance of non-invasive methods for monitoring health, especially glucose levels in diabetes.

Volatile Organic Compounds (VOCs)

• VOCs are organic compounds that evaporate at room temperature; examples include ethanol, acetone, methanol, and petrol.
• Higher concentrations of specific VOCs can indicate certain health conditions, e.g., diabetes patients exhaling more acetone.

Electronic Nose (E-Nose) Concept

• Mimics the human sense of smell using arrays of microsensors to detect and differentiate odors.
• Brains process patterns of smells; equivalent in e-nose is establishing an artificial neural network for pattern recognition.

Sensor Design and Fabrication

• Microengineering knowledge is crucial for creating arrays of micro and nanosensors to detect specific VOCs.
• Techniques include bulk micromachining and surface micromachining.
• Critical to select proper sensing materials; common options include indium tin oxide and zinc oxide.

Application of VOC Sensors

• VOC sensing has dual significance: environmental monitoring and medical diagnosis.
• Different diseases result in distinct VOC profiles, necessitating precise sensing technologies.

Health Impact of Pollution

• Air pollutants linked to respiratory and cardiovascular illnesses, as well as cancer risk.
• VOCs are harmful and common in many environments, such as newly painted areas emitting strong VOCs.

Sensor Development Techniques

• Two types of sensors explored:
  • VOC sensors for detecting volatile organic compounds.
  • Gas sensors for a broader spectrum of gaseous detection.
• Emphasis on design strategies to ensure flexibility and durability in sensor substrates.

Conclusion

• Understanding microengineering principles plays a vital role in advancing sensor technology for non-invasive disease diagnosis and environmental safety.

Sensor Design and Microengineering

• Diabetic individuals exhale higher concentrations of acetone compared to healthy individuals, which can be detected by specific sensors.
• Designing effective sensors requires expertise in microengineering and microtechnology to create nano-sized sensor arrays.
• Larger dimension sensors can be designed but may lack the precision needed for certain applications.

Air and Water Pollution Effects

• Air pollutants include carbon monoxide, particulate matter, ozone, lead, sulfur dioxide (SO2), nitrogen dioxide (NO2), and volatile organic compounds (VOCs).
• Water pollution involves contaminants such as bacteria, parasites, and chemicals, with concerns like antibiotic resistance.
• VOCs can lead to various health issues, including respiratory illnesses, cardiovascular diseases, nausea, skin irritation, and cancer risk.
• Newly painted surfaces can emit VOCs, highlighting the importance of avoiding exposure to such environments.

VOCs and Their Implications

• VOCs: Organic compounds that can evaporate at room temperature; examples include petrol, diesel, ethanol, acetone, methanol, butanol, and isopropyl alcohol.
• The concentration of VOCs in exhaled breath varies based on individual health conditions, presenting an opportunity for non-invasive disease diagnosis.
• A person’s breath contains VOCs in the parts per million (PPM) range, with unique profiles for different diseases.

Importance of VOC Sensing

• VOC sensing plays a crucial role in environmental monitoring and medical diagnostics.
• Two types of sensors discussed:
  • VOC sensors specifically for detecting volatile organic compounds.
  • Gas sensors for detecting various gases and pollutants.

Sensor Fabrication Techniques

• Different approaches for sensor fabrication:
  • Bulk micromachining for traditional sensor designs.
  • Combination of bulk and surface micromachining for enhanced sensor capabilities.
• Common sensing materials include indium tin oxide and zinc oxide, utilized in semiconducting oxides to improve sensor performance.

Flexible Sensor Design

• For flexible sensors, choosing the appropriate substrate is vital to prevent cracking and ensure durability.
• Familiarity with design software such as SolidWorks or CATIA is beneficial but not essential for microengineers.

Explore the fabrication techniques used in MEMS-based sensors from a clinical perspective. This quiz covers essential concepts in microengineering, focusing on applications like diabetes monitoring and electronic noses. Test your understanding of microfabrication methods and their significance in healthcare.