# A Low-Cost and Portable Smart Instrumentation for Detecting Colorectal Cancer Cells
## 1 Introduction  
The combined advancement in the field of molecular biology and optics has revolutionized the investigation methods used in the field of biology and chemistry. The progress in fluorescence microscopy and molecular tagging has also enabled the pathways to analyze the dynamics of cells with molecule-specific contrast [1, 2]. In recent years, these fluorescent microscopes have garnered a lot of attention, as they offer multiple benefits and possibilities including live-cell imaging, high-resolution images and localization of fluorescence in cells. However, these fluorescent microscopes are expensive as they use sensitive and sophisticated equipment/parts [3] making it affordable only to hospitals/institutions with sound financial resources. These microscopes also require a trained operator [4] in order to utilize their functionality efficiently, such as adjusting the illumination, optical alignment, correct lens changeovers, filtration techniques and capturing images. A few low-costfluorescent microscopes were developed recently [5; 6; 7] to make it more affordable to researchers from developing countries but the low resolution still obstructs its wide application. On the other hand, fluorimeters measure fluorescent signal intensity emitted from the dyes that are attached to the biological molecules as well as naturally fluorescent molecules based on their excitation and emission wavelengths. These devices are commonly used for monitoring chlorophyll [8; 9; 10] in water. Monitoring these fluorescent signal helps researchers to find out the presence of specific molecules in the targets of interest [11] based on signal intensity [12]. A recent work [12] showed the detection of breast cancer cells with the help of a fluorometer. However, these devices are often bulky and costly as well as vulnerable to inconsistent fluctuation caused due to the changing environment, sensors and instrument design, as well as calibration of the equipment/parts. Colorectal cancer is the third most common type of cancer diagnosed in both men and women. It is also the third most leading cause of cancer-related deaths in the United States [13]. However, diagnosing cancer requires the use of expensive equipment (such as magnetic resonance imaging (MRI)) as well as a trained operator, which limits its use in the developing countries. Furthermore, in many regions around the world, the resources are limited due to the high cost of instrumentation as well as lab supplies. Though colorectal cancer mortality rates have declined mainly due to the advancement in technology, early and effective screening is needed to further reduce associated mortalities. The most common clinical procedure employed for diagnosing cancer includes colonoscopy (the gold standard) [14] which is both invasive and relatively expensive. This procedure is complex and is accompanied by high costs of operation. Providing each individual with hands-on access to commercial equipment requires either multi-week training through a set of experiments or the deployment of multiple instruments, which therefore has been both cost and time prohibitive. The use of fluorescence microscopy to visualize living cells is often achieved via specific labelling of proteins [15] through antibody, bio-specific ligand or nanobody that is conjugated to a fluorophore. Fluorescent labelling is usually achieved by using a reactive derivative of the fluorophore, which specifically binds to a selective group contained in the target molecule. Several studies have shown the detection of cancer cells by labelling the proteins of interest. In association with the recent development of biomarker sciences, fluorescence imaging is being used as a tool to detect complex human diseases based on targetable biomarkers. For example, cancer cells express many biomarkers which can be utilized to develop fluorescent probes (e.g., fluorescent antibodies) and detect cancer tissues with fluorescent microscopy or imaging instruments [16; 17].