Table 2.

Summary of various breast cancer biosensors, comprising advantages, biomarkers, LOD, and their principles.

S. No.	Biosensors with Their Benefits	Principle	Biomarker	LOD	References
1.	Electrochemical (most authenticate and effective biosensor)	Monitoring by using three approaches (cyclic voltammetry/impedance spectroscopy/differential-pulse voltammetry)	miRNA-155	84.3 fM	[26]
		Developed aptasensor based on microgel particles incorporating gold nanoparticles	miRNA-21	1.35 aM	[27]
2.	Wearable (helpful for continuous monitoring of breast cancer biomarker)	A bra monitoring structure based on miniaturized wearable antennae	Breast Cancer	high fidelity and precise tumor localization	[35]
		Development of wearable device attached thermal sensors to brassiere (bra) fabric	BC	monitors temperature variations in the breasts	[36]
3.	LFA (highly affordable and portable biosensor)	Sandwich principle of nucleic acid hybridization based on GNPs	microRNAs (21/155/210)	0.073/0.061/0.085 nM	[40]
		Nucleic acid-based lateral flow assay (LFA) utilizing citrate-capped GNPs as a coloring agent.	p53 and PTEN	0.06 ng/mL and 0.125 ng/mL	[41]
4.	Smartphone (effective in pandemic situation or on-site monitoring)	Self-detection of early breast cancer application with infrared camera and deep learning	Breast Cancer	breast cancer diagnoses were correctly predicted	[43]
		Utilizing the IoT, machine learning, and cloud computing technology for the therapy of BC during the COVID-19 outbreak	Breast Cancer	-	[44]
		Smartphone-based detection followed by photo-electrochemical immunoassay	HER2	3.5 pg/mL	[45]
		The portable system is accompanied by a custom-designed Android application, and the smartphone itself is equipped with Bluetooth capabilities	microRNA-21 in saliva	concentration range of 1 × 10−4 M to 1 × 10−12 M	[46]