Point-of-care devices were originally designed to allow medical testing at or near the point of care by health-care professionals. Some point-of-care devices allow medical self-testing at home but cannot fully cover the growing diagnostic needs of eHealth systems that are under development in many countries. A number of easy-to-use, network-connected diagnostic devices for self-testing are needed to allow remote monitoring of patients’ health. This Outlook highlights the essential characteristics of diagnostic devices for eHealth settings and indicates point-of-care technologies that may lead to the development of new devices. It also describes the most representative examples of simple-to-use, point-of-care devices that have been used for analysis of untreated biological samples.

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Regulatory authorities require analytical methods for bacteria detection to analyze large sample volumes (typically 100 mL). Currently only the Membrane Filtration and the Most Probable Number assays analyze such large volumes, while other assays for bacteria detection (ELISA, lateral flow assays, etc.) typically analyze volumes 1000 times smaller. This study describes flow-through direct immunoassays (FTDI), a new methodology for the targeted detection of bacteria in liquid samples of theoretically any volume. Flow-through direct immunoassays are performed in fluid-permeable microwells (e.g., wells of a filter well plate) that have a membrane on their bottom where the bacteria are trapped before their detection using a direct immunoassay. Two versions of FTDI assays for the detection of E. coli in 10 mL of sample were developed. A rapid FTDI assay that can be completed in less than 2.5 h can detect E. coli bacteria in levels down to 17 CFU/mL, and an ultrasensitive FTDI assay that employs an additional bacteria culturing step to boost the sensitivity can detect E. coli bacteria in levels lower than 1 CFU/mL in less than 5.5 h. All the steps of the assays, including the immunoassay steps, the culturing step, and the analytical signal measurement step are performed inside the well plate to decrease the chance of contamination and ensure a safe, easy process for the user. The assays were assessed and validated in tap water, river water, and apple juice samples, and the results suggests that the assays are robust, precise, and accurate. When the assays are performed in 96-well filter plates, a filter well plate vacuum manifold and a multichannel peristaltic pump are also used, so multiple samples can be analyzed in parallel to allow highthroughput analysis of samples.

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Analytical tests/devices that are used outside laboratory settings are required to have a very simple analytical protocol to get clearance by regulatory authorities. This study describes sink/float magnetic immunoassays, a new type of rapid, mix‐and‐observe, instrument‐free tests for the detection of biomarkers in untreated biological samples that are very simple and might meet the simple‐to‐use criterion of authorities to be used in the field. These tests can tell whether an analyte is above or below a predetermined level within 25–45 minutes based on the sinking or floating of a mm‐sized sphere on the surface of which an immunoassay that uses reporter antibodies conjugated to superparamagnetic nanoparticles is performed. This manuscript describes the theory and proof‐of‐concept applications of sink/float magnetic immunoassays for the detection of C‐Reactive Protein, anti‐Treponema pallidum antibodies and E. coli bacteria.