# Exploring the Potential of Sensing for Breast Cancer Detection
## 6 Challenges for Existing Techniques and Prospects
Generally, this experiment can be performed in ambient conditions and can study the dynamic process. Transparent or semi-transparent materials can be considered for SERS treatment within the visible spectrum for detailed bonding information. There is freedom in the experimental setup to visualize a wide range of in situ capabilities, viz., temperature, environmental control, strain, chemical monitoring, etc. However, SERS is not free from the disadvantages. A laser is applied to the sample in SERS treatment, and the exciting laser selection is essential for extracting the bonding information because the laser is also sometimes responsible fordegrading the material. RS is also a low-probability light interaction. Our ability to detect light has improved, and the limited detection of most materials is around 1%. ECL is a non-radioactive, flexible, and fast process for detection. However, the complexities of applying this method are related to maintaining a favorable temperature and stable electrodes and the cross-interaction between the co-reactant and the luminophore. A quencher can be introduced further to amplify the intensity of ECL [176]. An ideal luminophore, which has a lower energy band gap, which means little energy is required to make an electron transition from the valance band to the conduction band, can be considered for ECL to improve the performance of ECL [176]. Modern quantum materials are used to design these highly efficient luminophores. There are several advantages to considering a QCM biosensor. A QCM biosensor has stable, high-sensitivity, and level-free detection capability [177]. So, the possible interference associated with the actual binding process can be ignored in this approach [177]. However, a QCM biosensor has some limitations. First, if there is non-uniform mass distribution on the quartz crystal, this leads to a frequency discrepancy. Second, the solution leak enhances the capacitive background current. Third, a minimum time, the upper limit on the scan rate, is required to locate the resonant frequency. Fourth, the QCM frequency is linearly dependent on the temperature [178]. The temperature variation can change the experimental setup. Fifth, there is noise due to the vibrating nature of the crystal. The electrochemical signal must be separated from the exciting signal. In most fluorescence biosensors, the fluorescence intensity is considered for detecting impurities. The instrument's condition and environmental factors can easily perturb the outcome fluorescence profile. In that case, the self-calibration of the two fluorescent emission bands has been addressed for ratiometric sensors to minimize the external effects on the fluorescence intensity profile [179,180]. In fluorescent resonance energy transfer (FRET) based ratiometric sensors, the ratio of two fluorescent emission bands is not affected by the concentration and fluctuation of the source [181]. Conjugated polymers are sometimes considered for delocalizing electrons and light harvesting, ultimately amplifying the fluorescence intensity output profile [181]. Flow cytometry is an optical setup to observe individual cell properties to differentiate abnormal cells from normal ones. In that case, the wavelength of the incident laser light is comparable to the size of the cell. Otherwise, the light-matter interaction will not provide detailed information about a single cell. On the other hand, this method can generate colossal data by considering a single cell, and this massive information can be categorized by employing the knowledge of machine learning [166, 167, 168, 169, 170, 171] to determine the binary outcomes and corresponding possibilities. Microfluidic biosensors are more compatible than non-microfluidic biosensors and can produce both quantitative and qualitative results within 3 h. The LOD for microfluidic biosensors is \(3\times 10^{3}\,\mathrm{CFU/mL}\), while the LOD for non-microfluidic biosensors is \(3\times 10^{4}\,\mathrm{CFU/mL}\).