Recently, microfluidic applications have replaced standard laboratory procedures with miniature devices aiming at diagnosing and monitoring medical disorders. Wellrecognized conventional microscopic techniques’ are still traditionally used for imaging in microfluidic technologies. However bulky and expensive nature of these microscopes is not compatible with next-generation point-of-care devices. Implementation of optical elements in miniaturized devices offers portable instrumentation as well as measurement accuracy and precision. Specifically, the integration of lensless imaging technologies with micro technologies has paved the way to develop novel devices. With this interest, two different applications of integrated lensless holographic microscopes were presented in this thesis. The first application includes the development of a new method of lensless holographic microscope-integrated microfluidic-based filtering to separate, purify and isolate circulating tumor microembolus from leukocytes according to their size and morphology. By using the advantages of microfiltration and lensless holographic microscope technologies, the developed method provides separation efficiency and purity of circulating tumor microembolus comparable with commercial cell separation devices. Another novel method, a lensless holographic microscope integrated magnetic levitationbased viscosity and density measurement of solutions, was introduced. The principle utilizes the use of microparticles as a kind of microsensor to correlate their levitation heights and velocities to the densities and viscosities of the solutions, where these particles are spiked. In the scope of this thesis, integrated lensless holographic microscope systems into microfluidic-based technologies may pave the way for the development of cost-effective and portable image-based novel devices.