Chemistry
The integration of chemistry in our cochlear implant project ensures biocompatibility, corrosion resistance, and durability through materials like titanium while optimizing electrical conductivity and long-term stability in the device. This chemistry-driven approach enhances both the functionality and safety of the implant for long-term use in the human body.
Integration
Thermal Stability
Thermal stability refers to the material's ability to maintain its properties under varying temperatures.
Battery Chemistry
The energy source for the cochlear implant (if portable) involves battery chemistry, specifically lithium-ion or lithium-polymer batteries.
Battery Chemistry
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Concept: The cochlear implant runs on a small battery, and its power source relies on efficient energy storage and energy conversion mechanisms. The chemistry of batteries involves the reversible chemical reactions that allow energy to be stored and released as electrical energy.
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Chemistry Principle: The most common battery used in medical devices is the lithium-ion battery, which relies on the movement of lithium ions between the positive and negative electrodes during charging and discharging.
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Application: Lithium-ion batteries are used in the cochlear implant to provide a long-lasting power source. The ability of lithium ions to move easily between the electrodes results in high energy density and efficiency, ensuring the implant can function for long periods on a single charge.
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Chemical Reaction in Lithium-Ion Battery: During discharge (when the battery is providing power): LiCoO2→LixCoO2 + xLi+ + xe− This reaction occurs at the positive electrode (cathode), where lithium ions are released.
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ΔL= αL0ΔT
Thermal Stability
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Concept: Materials like titanium, which are used in the structural and electrode components of the cochlear implant, must maintain their integrity under varying temperature conditions. Thermal expansion of materials can affect the performance and reliability of the implant.
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Chemistry/Physics Principle: Thermal expansion refers to the tendency of a material to change its dimensions in response to temperature changes. The coefficient of thermal expansion (CTE) indicates how much a material will expand or contract as the temperature changes. Materials with low CTE values are preferred for implants to avoid mechanical stress due to temperature fluctuations.
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For titanium, the coefficient of thermal expansion is around 8.6 × 10⁻⁶ /°C.
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For other materials like platinum (used in electrodes), the CTE is low, which helps prevent changes in size that could affect the function.
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Application: The titanium used in the cochlear implant retains thermal stability within the typical human body temperature range (36°C to 38°C) and does not significantly expand or contract under normal operating conditions. This ensures the structural integrity and reliable function of the implant over time.
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Formula for Thermal Expansion: The change in length of a material due to temperature change can be calculated by:
ΔL =αL0ΔT
where: -
ΔL = change in length,
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α = coefficient of thermal expansion,
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L0 = original length,
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ΔT = change in temperature.
