This thesis explores the development of multiplexed biosensors based on microneedle technology for the detection of critical physiological parameters, specifically potassium and pH levels. Microneedles, due to their micron-scale size, offer a minimally invasive approach to sampling interstitial fluid, making them ideal for continuous, real-time health monitoring. Their design allows for painless insertion into the skin, providing a seamless and non-invasive alternative to traditional sampling methods. The sensors utilize electrochemical detection, enhanced through the integration of advanced materials such as Iridium Oxide (IrOx), Polyaniline (PANI), and Poly(3,4-ethylenedioxythiophene) (PEDOT). These materials improve the sensors' sensitivity and selectivity, enabling accurate detection of potassium and pH.