Biomedical Sensory

TODO: REVIEW FOR PREVIOUS LESSONS

Sensitivity: $S=\cfrac{\Delta A_o}{\Delta A_i}$
Nonlinearity: $\gamma=\cfrac{\Delta max}{\gamma_m}\cdot 100%$

Biosensor

Structure
- Input: Substances
- Biological component on polymer membranes
- Transducer
  - Covnert physical/chemical changes into measurable electrical signal
  - Types of transducer
    - Electrodes: Oxygen electrode, ammonia electrode, CO2 electrode, pH electrode
    - Photoelectric converter: Photomultiplier tube
    - Thermoelectric converter: Thermistor
    - Semiconducter ISFET: detect the concentration of ions
- Output: Electrical signal
Classifications:
- Based on sensitive material
  - Enzyme based sensor
  - Microbial based sensor
  - Tissue based sensor
  - Cell based sensor
  - Immunosensor
- Based on Transducer
  - electrode based
  - thermal based
  - glowing based
  - semiconducter based
  - field based
  - electrochemical based
  - photoelectric based
Advantages
- high specificity and sensitivity
- good stability
- low cost
- tiny size
- in vivo
- rapid and continuous detection
- tiny sample required
- reusability
Electrochemical Sensor: Amperometric glucose Biosensor
- By measuring the consumption of $O_2$ or the generation of $H_2O_2$, we could indirectly measure the proportion of glucose
- $$GOD(FAD)+Glucose\rightarrow GOD(FADH_2)+ Glucolactone$$
- $$GOD(FADH_2)+O_2\rightarrow GOD(FAD)+H_2O_2$$
- In all: $Glucose+O_2\xrightarrow{GOD} Glucolactone+H_2O_2$
- 2 methods obtaining electrical signal
  - Using oxygen electrode to measure the exhaust of $O_2$
  - Using Pt as anode, Ag as cathode to measure the production of $H_2O_2$
Immunosensor
- Electrochemical based immunosensor
  - Current based
  - Potential based
  - Capacitance based
  - Conductance based
- Mass spectrometry based immunosensor
- Light-induce based immunosensor
  - Principle:
    - special substances $\Rightarrow$ immobilized light-emmiting enzyme $\Rightarrow$ emit photons $\Rightarrow$ photoelectric transducer $\Rightarrow$ electrical signal
  - Structure:
    - Single stranded DNA(ssDNA) probe
      - ssDNA probe immobilize and hybrid with target DNA (cDNA) and produce photons
    - Photoelectric transducer
  - Improvement: Optical fiber DNA immunosensor
    - Equipment:
      - fluorescenced ssDNA probe attached on the end of um-level fiber
      - fluorescence microscope on another end of the fiber
    - Sink the ssDNA probe into solution of target DNA $\Rightarrow$ Immobilization $\Rightarrow$ flourescent probes absorbed layser and emit photons $\Rightarrow$ Flourescence transfer back to the microscope $\Rightarrow$ CCD detect images.
- Thermal-based immunosensor
Immobilize technology of biosensor
- adsorption
- covalent bonding
- physical encapsulation
Piezoelectric ceramics
- $Q_x=d_{11}F_x$
- $Q_y=d_{12}\cfrac{a}{b}F_y=-d_{11}\cfrac{a}{b}F_y$

医学传感

Biomedical Sensory

TODO: REVIEW FOR PREVIOUS LESSONS

Biosensor