The research behind the platform
These papers map the science of analyzing volatile compounds in the headspace above urine and other biofluids: how those measurements are taken, what the resulting chemical signatures contain, and how they relate to human physiology and to the detection of disease. They describe the research field as a whole, not any single CareTech Human product. Below, they are grouped as six questions — from what the body emits to how a personal baseline is built.
- 01
Is there anything to measure?
The human volatilome
What the body emits, and how it is measured.
Journal of Breath Research · 2014
A review of the volatiles from the healthy human body
de Lacy Costello et al.
The first catalog of volatile compounds emitted by the human body. 1,840 compounds were assigned across breath, saliva, blood, milk, skin, urine (279 compounds) and feces in apparently healthy individuals.
Journal of Breath Research · 2021
A literature survey of all volatiles from healthy human breath and bodily fluids: the human volatilome
Drabińska et al.
The updated version of the 2014 catalog. Over 900 additional compounds have been reported since, and the authors argue that knowing the healthy range is what makes it possible to tell states apart.
Analytical Chemistry · 2023
Global urinary volatolomics with (GC×)GC-TOF-MS
Myridakis et al.
A method paper on how far urinary volatile profiling has come. Broader compound coverage while cutting the required urine volume five-fold, from 2 mL to 0.4 mL.
- 02
Can an instrument read it?
Digital olfaction
How a machine reads a smell.
Nature · 1982
Analysis of discrimination mechanisms in the mammalian olfactory system using a model nose
Persaud & Dodd
The paper that started the field. The authors proposed that olfaction works through broadly tuned receptors rather than highly specific ones, built an electronic nose on that principle, and showed it could reproducibly discriminate a wide variety of odours.
IEEE Sensors Journal · 2021
Artificial olfaction in the 21st century
Covington, Marco, Persaud, Schiffman & Nagle
A state-of-the-field review by the people who built it. It covers medical, food and environmental applications, and states plainly where the remaining gaps are: sensor technology, system design, manufacture and performance standards.
Science · 2023
A principal odor map unifies diverse tasks in olfactory perception
Lee et al.
A neural network learned to predict odor quality from molecular structure. On 400 molecules it had never seen, its odor profile matched a trained human panel more closely than the median panelist did.
- 03
Does ordinary life change it?
Everyday physiology
Exertion, digestion and recovery are visible in volatile chemistry.
Metabolomics · 2015
Changes in urine headspace composition as an effect of strenuous walking
Samudrala et al.
Urine headspace measured before and after exercise in 51 participants across four days of an endurance walking event. The volatile profile separated before and after walking on three of the four days, with acetic acid rising after exercise.
Metabolites · 2021
Exhaled breath reflects prolonged exercise and statin use during a field campaign
Henderson et al.
Three days of repeated long-distance walking, with breath sampled on site. Acetone and most other compounds rose after the first day and fell back toward baseline before the second, and a cluster of short-chain fatty acids appeared as a possible readout of gut microbial activity.
Gut Microbes · 2021
Noninvasive monitoring of fibre fermentation in healthy volunteers by analyzing breath volatile metabolites
Neyrinck et al.
Fifteen healthy volunteers received a fermentable dietary fibre or a placebo with breakfast. The fibre raised exhaled butyrate and five other volatile metabolites, peaking around six hours after intake.
- 04
Has anything serious been caught this way?
What volatile compounds have detected
Peer-reviewed clinical work on detecting disease from volatile signatures — part of the research field, not a product claim.
ACS Nano · 2017
Diagnosis and classification of 17 diseases from 1404 subjects via pattern analysis of exhaled molecules
Nakhleh et al.
The largest clinical test of a sensor array to date. Breath from 1,404 subjects with one of 17 conditions or none; blind experiments reached 86% accuracy, each condition showed its own pattern, and the result was cross-checked against GC-MS.
Biosensors · 2020
Sniffing out urinary tract infection: diagnosis based on volatile organic compounds and smell profile
Dospinescu, Tiele & Covington
Reviews how mass spectrometry, ion mobility spectrometry and electronic noses read volatiles from urine headspace to identify a bacterial pathogen, in some work within minutes rather than the 24 to 72 hours a culture takes.
Biosensors · 2018
Non-invasive diagnosis of diabetes by volatile organic compounds in urine using FAIMS and Fox4000 electronic nose
Esfahani et al.
140 urine samples, 73 from people with type 2 diabetes and 67 from healthy controls, analyzed with two different electronic nose technologies. A metabolic state, not an infection, separated on urinary volatiles alone.
Metabolites · 2020
Urinary volatile organic compound analysis for the diagnosis of cancer: a systematic literature review and quality assessment
Wen et al.
Thirteen studies and 1,266 participants across five cancer types. Forty-eight urinary compounds showed high diagnostic performance and the profiles were distinctive per cancer type, though the authors note that differences in study design produced inconsistencies between studies.
- 05
Why the bathroom?
The toilet as a measurement point
Why the bathroom, and what it takes to do this at home.
Nature Biomedical Engineering · 2020
A mountable toilet system for personalized health monitoring via the analysis of excreta
Park et al.
An add-on module that read urinalysis strips from images, measured urine flow and volume by computer vision, and classified stool at a level comparable to trained medical personnel. Pilot study of 21 participants.
Nature Reviews Urology · 2022
Toilet-based continuous health monitoring using urine
Tasoglu
The case for urine as the sample: produced in large volumes daily, collected with zero pain and no change to routine, and currently discarded without being measured. The review also names the open problems of user acceptance, privacy and test frequency.
Science Translational Medicine · 2023
Passive monitoring by smart toilets for precision health
Ge et al.
Treats smart toilets as a serious tool for home monitoring, and works through the consent and privacy questions that passive measurement raises.
- 06
Why does it take time?
Why a personal baseline
One reading is a snapshot. The comparison that matters is you against yourself.
npj Digital Medicine · 2019
Real-time health monitoring through urine metabolomics
Miller et al.
Two people collected every urine sample for 10 days, 109 in total, tracked by mass spectrometry alongside nutrition, exercise and sleep data. Coffee, alcohol and a dose of acetaminophen were all visible in the chemistry.
Nature Medicine · 2019
A longitudinal big data approach for precision health
Schüssler-Fiorenza Rose et al.
109 people profiled quarterly for up to eight years. Following each person against their own history produced more than 67 clinically actionable findings, most of which a single population-referenced test would have missed.
Science Translational Medicine · 2021
Continuous health monitoring: an opportunity for precision health
Gambhir, Ge, Vermesh, Spitler & Gold
Argues for monitoring at home rather than at intervals in clinic, and is direct about what stands in the way: validating the technology and turning continuous data into something a person can act on.
Building on this field with us?
We talk with clinicians, researchers and partners who want to put passive volatile sensing to work.