Important technologies for POC assessment of undernutrition
| Technology | TRL | Cost (approx.) | Information provided | Mode of deployment | Interpretation of results | Suitability for LMICs (1–5) | Development required |
| Capsule systems | |||||||
| Wireless capsule endoscopy | 9 | $$$ | Villous morphology (indirect) | IH | Manual interpretation by specialist, automated image analysis feasible | 2 | – |
| Tethered capsule OCT | 8 | $$$ | Villous morphology (direct) | IH/POC | Manual interpretation by specialist (training required), automated analysis feasible | 3 | POC validation |
| Sampling/biopsy capsules | 5 | $$$ | Microbiota, biomarker quantification, metabolic profiling, villous morphology (via histopathology) | IH (sample freezing and shipping required) | Laboratory analysis required (eg, pathology, MS, etc) | 2 | Validation of location specific sampling |
| Optical spectroscopy | |||||||
| Transcutaneous fluorescence spectroscopy | 5 | $ | Permeability | POC | Automated, on-sensor analysis | 5 | Deployable device development, human validation |
| Raman spectroscopy | 4 | $$ | Translocation, microbiota, breath sample analysis | POC | Automated analysis feasible (algorithm development required) | 3 | Sample preparation techniques, device development |
| Portable sequencing | |||||||
| MinION | 7 | $$ | Microbiota/microbiome, biomarker quantification, metabolic profiling | POC | On-site (POC) analysis using laptop | 3 | Sample preparation techniques, POC validation |
| SmidgION | 6 | $$ | Microbiota/microbiome, biomarker quantification, metabolic profiling | POC | On-site (POC) analysis using laptop or smartphone | 4 | Sample preparation techniques, POC validation |
| Breath tests | |||||||
| Untargeted | 9 | $$ | Microbiota, biomarker quantification, metabolic profiling | POC (sample storage and shipping required) | Laboratory analysis required | 3 | Validation of biomarkers and sample stability, sample storage technology |
| Targeted | 8 | $$ | Microbiota, biomarker quantification, metabolic profiling | POC | Laboratory analysis required | 5 | Devices for POC analysis, identification and validation of biomarkers |
| Immune function | |||||||
| Smartphone-based ELISA/LFIA | 6 | $ | Inflammatory biomarker quantification, immune function (indirect) | POC | Automated, on-sensor analysis | 5 | Validation for EE biomarkers, device/system optimisation |
| Miniaturised metabolomics | |||||||
| Paper strip metabolomics | 8 | $ | Biomarker quantification, metabolic profiling | POC (sample shipping required) | Laboratory analysis required | 4 | Validation of biomarker/metabolite stability |
| Portable mass spectrometry | 3 | $$ | Biomarker quantification, metabolic profiling | POC | Automated, on-site analysis feasible (significant development required) | 4 | Device/system development |
The most promising technologies discussed in this article are highlighted here. They are compared against one another in terms of their TRL, cost, the information that they provide, their mode of deployment, the way in which results are interpreted, their suitability for use in LMICs and the further development required. TRL is ranked on a scale of 1–9 (9 represents a mature, commercially available technology; 1 represents an initial concept). Mode of deployment is classed as either IH or POC, with POC referring to use in primary care settings, rural health facilities or domestic environments. Where necessary, the need to freeze and/or ship samples for analysis is also noted. As costs vary according to location and as some technologies have not yet reached market status, costs are provided on a relative scale only (ie, $, $$ or $$$). The suitability for LMICs is rated on a coarse scale of 1–5, with 1 indicating low suitability and 5 indicating high suitability. Scores were generated via qualitative assessment based on a range of factors (including cost, ease of use, need for sample shipping, need for expert analysis, invasiveness, etc).
IH, in-hospital; LFIA, lateral flow immunoassay; LMICs, low-income and middle-income countries; MS, mass spectrometry; OCT, optical coherence tomography; POC, point-of-care; TRL, technological readiness level.