Norlaili Saad
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Norlaili Saad
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Norlaili, Saad
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  • Publication
    Optimization of intraocular capacitive pressure sensor
    (Universiti Malaysia Perlis (UniMAP), 2018-11)
    Norlaili Saad
    ;
    N. Soin
    Intraocular MEMS capacitive pressure sensors are useful for measuring intraocular pressure (IOP) for Glaucoma patients. For normal person, IOP reading range within 10-21mmHg. For IOP applications, compatible biomedical sensors are required to operate in the range of 0-8 kPa (0-60mmHg). Intraocular MEMS capacitive pressure sensors are widely used in IOP measurement because it provides higher sensitivity to pressure, low noise, low temperature sensitivity and micro in size. In this research project, a corrugated MEMS capacitive pressure sensor is designed and demonstrated using COMSOL Multiphysics software. Result obtained from the simulation is the deflection of the corrugated diaphragm when 8kPa pressure is applied. From the diaphragm deflection, sensors mechanical sensitivity, capacitance sensitivity and residual stress varies with the pressure applied. When corrugation depth is increased, maximum deflection will decrease, hence the capacitance value is increased respectively. Capacitance sensitivity for corrugation depth, H=32 μm is obtained at 6.8451x10-3 fF/Pa which is 0.684% higher than flat diaphragm’s capacitance sensitivity. From the simulation, it is proven that residual stress for corrugated diaphragm is 63.147 MPa which is lower than flat diaphragms residual stress. The optimized parameter for corrugation depth is at H=45 μm which has higher capacitance sensitivity and smallest residual stress.
      3  13
  • Publication
    Intraocular MEMS Capacitive Pressure Sensor
    ( 2021-01-01)
    Anas Mohd Noor
    ;
    Zulkarnay Zakaria
    ;
    Norlaili Saad
    Microelectromechanical system (MEMS) sensors are suitable for measuring intraocular pressure (IOP). IOP measurement is useful for monitoring diseases such as glaucoma. The average pressure range for healthy persons is within 10–20 mmHg. A pressure beyond this range could damage the eye nerves and causes of blindness. Thus, a sensor for measuring the pressure should provide excellent accuracy and sensitivity. Intraocular capacitive pressure sensors are widely used in measurement of IOP. They offer high sensitivity and low noise, including invariance to temperature. Thus, the capacitive pressure sensor is performed better than other types of sensing methods. In this work, capacitive pressure sensors are designed and analyzed using FEM. The sensitivity and performance of a corrugated diaphragm, slot-type, square, and circular types of sensors designed are analyzed. Different shape of the sensor provides a different characteristic such as sensors pressure sensitivity, mechanical stress, and maximum deflection. As a result, corrugated diaphragm and slot-type sensors designed performs better than the flat diaphragm and non-slotted sensors designed. We show that four slotted non-corrugated square and circular designs have a high sensitivity, which is 0.157 mF higher than the eight slotted design. However, for corrugated design, eight slotted shows sensitivity is 0.147 mF higher and linearity analysis than four slotted sensor design. Circular shape design for eight slotted design, on the other hand, have 0.631 mF higher than the four slotted design. Corrugated design is more sensitive when a load is applied, while slotted design reduces the effect of residual stress and stiffness of the diaphragm. Thus, it is an advantage of using the FEM method for further analysis of sensor performance optimization.
      1  26