Design, Modeling and Characterization of Printed Passive Elements on Medical Hydrocolloids

  • Haneen AlSuradi

Student thesis: Master's Thesis

Abstract

Printing passive elements on flexible substrates is an affordable and a convenient method that can be used to integrate electronics and sensing mechanisms into clothing. All three elements (Spiral Inductors, Interdigital Capacitors and Serpentine Resistors) can be printed using different geometries that are well-known and used in Microwave Integrated Circuits (MICs) and PCB mediums. In this work, hydrocolloid dressings from 3M (TegadermTM) with planar dimensions of 10cmx10cm and thickness of around 1mm were used as flexible substrates for printing passives. High resolution SEM and impedance analyzer were both used to physically and electrically characterize the substrate, respectively. Passives were screen printed using Paron-910 silver conductive paste and a 90um mesh size leading to a metallization thickness of ~20um. Prior printing, the water-resistant surface of the hydrocolloid was coated with Polyvinyl Acetate (PVA) which is dense enough to fill the un-even features of the surface while being sparse enough to maintain flexibility. More than 100 designs were created and simulated sweeping wide range of the passives' geometrical parameters. Accurate analytical models for inductance, capacitance and resistance considering the hydrocolloid's environment were selected based on their performance with respect to the FEM simulations. Selected models were empirically tuned and thickness of metallization, which is usually ignored in available models, was taken into account. Tuned models match simulations with a mean percentage error of < 5%. Extreme geometrical cases were printed and characterized using LCR meter for which they matched models within around 6% error. It was found that within the surface area of the hydrocolloid, capacitance and Inductance ranging between 0.9pF< C < L < 78.4uH can be achieved, respectively. Resistance is a strong function of thickness and thus very dependent on the screen-printing parameters. Adopting hydrocolloids as mediums for integrating electronics can significantly boost the prevalence of attachable biomedical SoCs due to their affordability, flexibility and familiarity in the medical domain.
Date of AwardDec 2016
Original languageAmerican English
SupervisorJerald Yoo (Supervisor)

Keywords

  • Spiral Inductors
  • Interdigital Capacitors
  • Serpentine Resistors
  • Microwave Integrated Circuits
  • Wearable Electronics
  • Screen Printing
  • Hydrocolloid.

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