Point‐of‐care testing (POCT) has progressed from early “near‐patient” blood analyses and the first home glucose meters to a diverse toolkit of chemometric methods and miniaturized devices designed for rapid, user‐friendly diagnosis outside centralized laboratories. This chapter traces that evolution and critically appraises the principal detection modalities—colorimetric, fluorescence, chemiluminescence, electrochemical, surface plasmon resonance (SPR), and surface‐enhanced Raman spectroscopy (SERS)—and the instruments that deploy them, including lateral flow devices (LFDs), lab‐on‐a‐chip (LOC), lab‐on‐a‐disc (LOAD), miniaturized PCR, and isothermal nucleic acid amplification platforms. We highlight practical integrations for viral diagnostics with case studies in HIV and COVID‐19, spanning improved antigen capture (e.g., pretreatment for p24), aptamer‐enabled sensing across electrochemical/SPR/SERS readouts, amplification‐coupled and amplification‐free CRISPR assays, and smartphone‐centric readers. Despite clear gains in portability, turnaround time, and connectivity, significant barriers remain: sensitivity/specificity (particularly for LFDs), limited multiplexing, workflow complexity, provider awareness and trust, and scale‐up hurdles tied to fabrication, ancillary hardware, and lack of standardization. We outline engineering routes to higher analytical performance (flow control, capture‐element orientation, signal amplification, and target enrichment) and emphasize the emerging role of artificial intelligence for automated interpretation, epidemiologic analytics, and health‐system integration. With half of WHO priority epidemic diseases still lacking POC tests, coordinated advances in materials, microfabrication, assay chemistry, automation, and AI—across academia, industry, and policy—are essential to deliver sensitive, affordable, and scalable POCT that can reshape infectious‐disease surveillance and care.
