Table 1.

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.