Early disease detection and in-time health monitoring via novel sensing systems is highly demanded for modern medicine and health management. Recent development in nanotechnology and nanomaterials such as functionalized nanostructured metal-oxide semiconductors and newly discovered two-dimensional Ti3C2 MXenes have offered exciting areas of research as nanomaterial-based biomedical sensing devices. In this thesis, two major nanomaterials, KWO for application in diabetes and MXene for cancer management and further improvement of the KWO diabetes sensor, are intensively researched. KWO shows great potential as a breath acetone sensor, which can be utilized to monitor and diagnose diabetes. It also shows the unique ferroelectric property, which allows for a room-temperature sensing operation. Synthesis methods and characterization are done to further the understanding of KWO as an acetone sensor and further improve its capability towards becoming the cornerstone of a handheld biomedical sensor that is non-invasive, portable, and easy-to-use. Continuing, Ti3C2 MXenes are studied and characterized under various synthesis conditions to create both accordion-like structures with varying gap widths, and single-to-few layered nanosheets created by the intercalation of Li+ ions. Additionally, a new sensor based on 2D nanosheets, Ti3C2 MXene, has been designed and used for the sensing response to 8-HOA and PGE2 in lung cancer cells. The preliminary results indicate an important conclusion: this new Ti3C2-based sensor can provide a convenient and simple method for anti-cancer treatment guidance. Finally, a nanocomposite is synthesized using both KWO and Ti3C2 MXenes to improve the acetone sensor’s sensitivity and selectivity by majorly reducing humidity cross-interference.