News, Analysis, Trends, Management Innovations for
Clinical Laboratories and Pathology Groups

Hosted by Robert Michel

News, Analysis, Trends, Management Innovations for
Clinical Laboratories and Pathology Groups

Hosted by Robert Michel
Sign In

Breath Sample Is Used by Opteev Technologies’ Combined COVID/Influenza/RSV Screening Device with 95% Sensitivity and 90% Specificity

Clinical laboratories and point-of-care settings may have a new diagnostic test if this novel handheld device and related technology is validated by clinical trials

Efforts to develop breath analyzers that accurately identify viral infections, such as SARS-CoV-2 and Influenza, have been ongoing for years. The latest example is ViraWarn from Opteev Technologies in Baltimore, Maryland, and its success could lead to more follow-up PCR tests performed at clinical laboratories.

ViraWarn is a pocket-size breath analyzer that detects COVID-19, influenza, and respiratory syncytial virus (RSV) in about a minute, according to an Opteev news release. The technology company just submitted ViraWarn to the US Food and Drug Administration (FDA) for Pre-Emergency Use Authorization (Pre-EUA).

“Breath is one of the most appealing non-invasive sample types for diagnosis of infectious and non-infectious disease,” said Opteev in its FDA Pre-EUA application. “Exhaled breath is very easy to provide and is less prone to user errors. Breath contains a number of biomarkers associated with different ailments that include volatile organic compounds (VOCs), viruses, bacteria, antigens, and nucleic acid.”

Further clinical trials and the FDA Pre-EUA are needed before ViraWarn can be made available to consumers. In the meantime, Opteev announced that the CES (Consumer Electronic Show) had named ViraWarn as a 2023 Innovation Award Honoree in the digital health category. 

Conrad Bessemer

“ViraWarn is designed to allow users an ultra-fast and convenient way to know if they are spreading a dangerous respiratory virus. With a continued increase in COVID-19 and a new surge in RSV and influenza cases, we’re eager to bring ViraWarn to market so consumers can easily blow into a personal device and find out if they are positive or negative,” said Conrad Bessemer (above), Opteev President and Co-Founder, in a news release.

Opteev is a subsidiary of Novatec, a supplier of machinery and sensor technology, and a sister company to Prophecy Sensorlytics, a wearable sensors company. 

The ViraWarn breath analyzer uses a silk-based sensor that “traces the electric discharge of respiratory viruses coupled with an artificial intelligence (AI) processor to filter out any potential inaccuracies,” according to the news release.

Here is how the breath analyzer (mouthpiece, attached biosensor chamber, and attached printed circuit board chamber) is deployed by a user, according to the Opteev website:

  • The user turns on the device and an LED light indicates readiness.
  • The user blows twice into the mouthpiece.
  • A carbon filter stops bacteria and VOCs and allows virus particles to pass through.
  • As “charge carriers,” virus particles have a “cumulative charge.”
  • In a biosensor chamber, virus particles create a change in “electrical resistivity.”
  • Electrical data are forwarded to the AI processor.
  • The AI processer delivers a result.
  • Within 60 seconds, a red signal indicates a positive presence of a virus and a green signal indicates negative one.

“The interaction of the virus with a specially designed liquid semiconductive medium, or a solid polymer semiconductor, generates changes in the conductivity of the electrical biosensor, which can then be picked up by electrodes. Such electrical data can be analyzed using algorithms and make a positive or negative call,” explains an Opteev white paper on the viral screening process.

While the ViraWarn breath analyzer can identify the presence of a virus, it cannot distinguish between specific viruses, the company noted. Therefore, a clinical laboratory PCR test is needed to confirm results.

Other Breath Tests

Opteev is not the only company developing diagnostic tests using breath samples.

In “Will Blowing in a Device Be Useful in Screening for COVID-19? FDA Grants Its First EUA for a Breathalyzer SARS-CoV-2 Screening Test,” Dark Daily reported on the FDA issuing an EUA in 2022 for the InspectIR COVID-19 Breathalyzer, the first test to detect compounds in breath samples linked to SARS-CoV-2 infection, an FDA statement noted.

And in “NIST Scientists Enhance Frequency Comb Breathalyzer Enabling It to Detect Multiple Disease Biomarkers,” we covered how researchers at JILA, a research center jointly operated by the National Institutes of Standards and Technology (NIST) and the University of Colorado Boulder, have developed a breath test that can detect and monitor four disease biomarkers at one time with the potential to identify six more.

For clinical laboratory managers and pathologists, Opteev’s ViraWarn is notable in breath diagnostics development because it is a personal hand-held tool. It empowers people to do self-tests and other disease screenings, all of which would need to be confirmed with medical laboratory testing in the case of positive results.

Further, it is important to understand that consumers are the primary target for this novel diagnostic device. This is consistent with investor-funding companies wanting to develop testing solutions that can be used by consumers. At the same time, a device like ViraWarn could be used by clinical laboratories in their patient service centers to provide rapid test results.  

Donna Marie Pocius

Related Information:

Pocket-Sized Breath Analyzer Detects COVID-19, RSV, Influenza in Under 60 Seconds

COVID-19, RSV, and Influenza Breath Analyzer, ViraWarn, Wins CES 2023 Innovation Award

Baltimore Company Launches Device That Detects COVID-19, Flu

ViraWarn Pre-EUA Application

The Missing Piece in the Fight Against the Pandemic is Finally Here: The Evolution of Screening for COVID-19

FDA Authorizes First COVID-19 Diagnostic Test Using Breath Samples

Will Blowing in a Device Be Useful in Screening for COVID-19? FDA Grants Its First EUA for a Breathalyzer SARS-CoV-2 Screening Test

NIST Scientists Enhance Frequency Comb Breathalyzer Enabling It to Detect Multiple Disease Biomarkers

German Researchers Create Non-invasive Lab-on-a-Chip Biosensor That Detects Antibiotic Levels from Breath Samples

Should the device prove effective, it could replace invasive point-of-care blood draws for clinical laboratory testing during patient drug therapy monitoring

What if it were possible to perform therapeutic drug monitoring (TDM) without invasive blood draws using breath alone? Patients fighting infections in hospitals certainly would benefit. Traditional TDM can be a painful process for patients, one that also brings risk of bloodline infections. Nevertheless, regular blood draws have been the only reliable method for obtaining viable samples for testing.

One area of critical TDM is in antibiotic therapy, also known as personalized antibiotherapy. However, for antibiotic therapy to be successful it typically requires close monitoring using point-of-care clinical laboratory testing.

Now, a team of engineers and biotechnologists from the University of Freiburg in Germany have developed a biosensor that can use breath samples to measure antibiotic concentrations present in blood, according to a University of Freiburg press release.

The team’s non-invasive collection method requires no needle sticks and can allow for frequent specimen collections to closely monitor the levels of an antibiotic prescribed for a patient. The biosensor also provides physicians the ability to tailor antibiotic regimens specific to individual patients, a core element of precision medicine.

The researchers published their findings in the journal Advanced Materials, titled, “Biosensor-Enabled Multiplexed On-Site Therapeutic Drug Monitoring of Antibiotics.”

Can Dincer, PhD
 
“Until now researchers could only detect traces of antibiotics in the breath,” said Can Dincer, PhD (above), Junior Research Group Leader at the University of Freiburg, and one of the authors of the study, in the press release. “With our synthetic proteins on a microfluid chip, we can determine the smallest concentrations in the breath condensate and [how] they correlate with the blood values.” Should the breath biosensor prove effective in clinical settings, painful blood draws for clinical laboratory testing at the point of care could become obsolete. (Photo copyright: Conny Ehm/University of Freiburg.)

Can a Breath Biosensor Be as Accurate as Clinical Laboratory Testing?

The University of Freiburg’s biosensor is a multiplex, microfluid lab-on-a-chip based on synthetic proteins that react to antibiotics. It allows the simultaneous measurement of several breath samples and test substances to determine the levels of therapeutic antibiotics in the blood stream.

To perform their research, the University of Freiburg team tested their biosensor on blood, plasma, urine, saliva, and breath samples of pigs that had been given antibiotics. The results the researchers achieved with their device using breath samples were as accurate as standard clinical laboratory testing, according to the press release.

The microfluidic chip contains synthetic proteins affixed to a polymer film via dry film photoresist (DFR) technology. These proteins are similar to proteins used by drug-resistant bacteria to sense the presence of antibiotics in their environment. Each biosensor contains an immobilization area and an electrochemical cell which are separated by a hydrophobic stopping barrier. The antibiotic in a breath sample binds to the synthetic proteins which generates a change in an electrical current. 

“You could say we are beating the bacteria at their own game,” said Wilfried Weber, PhD, Professor of Biology at the University of Freiburg and one of the authors of the research paper, in the press release.

Rapid Monitoring at Point-of-Care Using Breath Alone

The biosensor could prove to be a useful tool in keeping antibiotic levels stable in severely ill patients who are dealing with serious infections and facing the risk of sepsis, organ failure, or even death. Frequent monitoring of therapeutic antibiotics also could prevent bacteria from mutating and causing the body to become resistant to the medications.

“Rapid monitoring of antibiotic levels would be a huge advantage in hospital,” said H. Ceren Ates, PhD, scientific researcher at the University of Freiburg and one of the authors of the study in the press release. “It might be possible to fit the method into a conventional face mask.”

Along those lines, the researchers are also working on a project to create wearable paper sensors for the continuous measurement of biomarkers of diseases from exhaled breath. Although still in the development stages, this lightweight, small, inexpensive paper sensor can fit into conventional respiratory masks, according to a University of Freiburg press release.

Other Breath Analysis Devices Under Development

Devices that sample breath to detect biomarkers are not new. Dark Daily has regularly reported on similar developments worldwide.

In “NIST Scientists Enhance Frequency Comb Breathalyzer Enabling It to Detect Multiple Disease Biomarkers,” we reported on research conducted at JILA, a research center jointly operated by the National Institutes of Standards and Technology (NIST) and the University of Colorado Boulder, that could pave the way for real-time, noninvasive breath analysis to detect and monitor diseases, and potentially eliminate the need for many blood-based clinical laboratory tests.

And in “Will Blowing in a Device Be Useful in Screening for COVID-19? FDA Grants Its First EUA for a Breathalyzer SARS-CoV-2 Screening Test,” Dark Daily covered the FDA’s first ever emergency use authorization (EUA) for a portable breath test device designed to screen for SARS-CoV-2 infection. Developed by InspectIR Systems, the COVID-19 Breathalyzer identifies a chemical signature associated with SARS-CoV-2 in about three minutes with 91.2% sensitivity and 99.3% specificity.

Thus, University of Freiburg’s non-invasive lab-on-a-chip biosensor is worth watching. More research is needed to validate the effectiveness of the biosensor before it could be employed in hospital settings, however, monitoring and managing antibiotic levels in the body via breath samples could prove to be an effective, non-invasive method of providing personalized antibiotic therapy to patients.

Clinical trials on human breath samples are being planned by the University of Freiburg team. This type of precision medicine service may give medical professionals the ability to maintain proper medication levels within an optimal therapeutic window.

JP Schlingman

Related Information:

Antibiotic Levels Measurable in Breath for the First Time

Biosensor-Enabled Multiplexed On-Site Therapeutic Drug Monitoring of Antibiotics

A Breath of Fresh Information

NIST Scientists Enhance Frequency Comb Breathalyzer Enabling It to Detect Multiple Disease Biomarkers

Will Blowing in a Device Be Useful in Screening for COVID-19? FDA Grants Its First EUA for a Breathalyzer SARS-CoV-2 Screening Test

NIST Scientists Enhance Frequency Comb Breathalyzer Enabling It to Detect Multiple Disease Biomarkers

Device could pave the way for real-time, noninvasive breath analysis to detect and monitor diseases and be a new service medical laboratories can offer

Breathalyzer technology is not new, but until now human breath detection devices have not been comparable to clinical laboratory blood testing for disease detection and monitoring. That may soon change and there are implications for clinical laboratories, partly because breath samples are considered to be non-invasive for patients.

Scientists with JILA, a research center jointly operated by the National Institutes of Standards and Technology (NIST) and the University of Colorado Boulder, recently increased the sensitivity of their laser frequency comb breathalyzer one thousand-fold. This created a device that can detect four disease biomarkers simultaneously, with the potential to identify six more, according to an NIST news release.

Medical laboratory scientists will understand the significance of this development. JILA’s enhanced breathalyzer device could pave the way for real-time, noninvasive breath analysis to detect and monitor diseases, and potentially eliminate the need for many blood-based clinical laboratory tests.

The JILA researchers published their findings in the journal Proceedings of the National Academy of Sciences (PNAS), titled, “Ultrasensitive Multispecies Spectroscopic Breath Analysis for Real-Time Health Monitoring and Diagnostics.”

Measuring Light to Spot Biomarkers of Disease

During their research, physicist Jun Ye, PhD, and David Nesbitt, PhD, both Fellows at JILA and professors at University of Colorado Boulder, detected and monitored four biomarkers in the breath of a volunteer:

These chemicals can be indicators of various health conditions. Methane in the breath, for example, can indicate intestinal problems.

The researchers say the JILA breathalyzer also could detect six additional biomarkers of disease without any further modifications to the device. They would include:

Jun Ye, PhD and David Nesbitt, PhD
 
NIST/JILA Research Fellows Jun Ye, PhD (left), and David Nesbitt, PhD (right) of the University of Colorado Boulder, “built a breathalyzer that identifies biomarkers of disease by measuring the colors and amounts of light absorbed as a laser frequency comb passes through breath samples inside a glass tube,” according to an NIST news release. Should they succeed in creating a portable version, their noninvasive device could become an option compared to conventional clinical laboratory blood testing methods used to identify and monitor diseases. (Photos copyright: University of Colorado Boulder.)
 

“Determining the identity and concentration of the molecules present in breath is a powerful tool to assess the overall health of a person, analogous to blood testing in clinical medicine, but in a faster and less invasive manner,” the researchers wrote in PNAS.

“The presence of a particular molecule (or combination of molecules) can indicate the presence of a certain health condition or infection, facilitating a diagnosis. Monitoring the concentration of the molecules of interest over time can help track the development (or recurrence) of a condition, as well as the effectiveness of the administered treatment,” they added.

How the JILA Breathalyzer Detects Biomarkers

According to a 2008 NIST news release, JILA researchers had developed a prototype comb breathalyzer in that year. However, the research did not continue. But then the COVID-19 pandemic brought the JILA/NIST laboratories focus back to the breathalyzer with hopes that new research could lead to a breath test for detecting the SARS-CoV-2 coronavirus and other conditions.

“We are really quite optimistic and committed to pushing this technology to real medical applications,” Ye said in the 2021 NIST news release.

Analytical Scientist explained that JILA’s new and improved breathalyzer system “fingerprints” chemicals by measuring the amount of light absorbed as a laser frequency comb passes back and forth through breath samples loaded into a mirrored glass tube.

JILA’s original 13-year-old prototype comb analyzed colors and amounts of light in the near-infrared band. However, JILA’s recent improvements include advances in optical coatings and a shift to analyzing mid-infrared band light, allowing detection sensitivity up to parts-per-trillion level, a thousand-fold improvement over the prototype. 

Corresponding study author Jutta Toscano, PhD, postdoctoral researcher at the University of Basel in Switzerland and previously Lindemann fellow at JILA, told Physics World the new frequency comb can “probe the molecular fingerprint region where fundamental, and more intense, spectroscopic transitions are found.

“By matching the frequency of the comb teeth with the cavity modes—the ‘standing modes’ of the cavity—we can increase the interaction path length between molecules inside the cavity and laser light by a factor of around 4000, equivalent to an effective path length of a few kilometers,” she added. “We then probe the light that leaks out of the cavity by sending it into an FTIR [Fourier-transform infrared] spectrometer to find out which exact comb teeth have been absorbed and by how much. In turn, this tells us which molecules are present in the breath sample and their concentration.”

Even Hippocrates Studied Breath

Ye noted in the NIST statement that JILA is the only institution that has published research on comb breathalyzers.

In their PNAS paper, the researchers wrote, “Breath analysis is an exceptionally promising and rapidly developing field of research, which examines the molecular composition of exhaled breath. … Despite its distinctive advantages of being a rapid, noninvasive technique and its long history dating back to Hippocrates, breath analysis has not yet been as widely deployed for routine diagnostics and monitoring as other methods, such as blood-based analysis.

“We have shown that this technique offers unique advantages and opportunities for the detection of light biomarkers in breath,” the researchers noted, “and it is poised to facilitate real-time, noninvasive monitoring of breath for clinical studies, as well as for early detection and long-term monitoring of temporary and permanent health conditions.”

Validation of these findings and further design research to make the system portable are required before JILA’s frequency comb breathalyzer can become a competitor to clinical laboratory blood tests for disease identification and monitoring. Nevertheless, JILA’s research brings breathalyzer technology a step closer to offering real-time, non-invasive analysis of human biomarkers for disease.

Andrea Downing Peck

Related Information:

Ultrasensitive Multispecies Spectroscopic Breath Analysis for Real-Time Health Monitoring and Diagnostics

Ultrasensitive Frequency Comb Breathalyzer Targets Real-Time Disease Diagnosis

JILA’s Comb Breathalyzer Is Now a Thousand-Fold More Sensitive to Disease Biomarkers

Breath Analysis with a (Very) Fine Toothed Comb

Optical ‘Frequency Comb’ Can Detect the Breath of Disease

Will Blowing in a Device Be Useful in Screening for COVID-19? FDA Grants Its First EUA for a Breathalyzer SARS-CoV-2 Screening Test

InspectIR COVID-19 Breathalyzer identifies a chemical signature associated with SARS-CoV-2 in about three minutes with 91.2% sensitivity and 99.3% specificity One company is hoping that it can make breathalyzers a viable, easier way to screen for SARS-CoV-2. It will soon have the opportunity to learn if consumers will accept this form of screening for COVID-19, as its device recently obtained an Emergency Use Authorization from the FDA. On April 14, 2022, InspectIR Systems, LLC, of Frisco,...

FDA Expands Approval of Gastric Emptying Breath Test for Gastroparesis to Include At-home Administration Under Virtual Supervision

It may not be a boom trend, but more non-invasive diagnostic tests are coming to market as clinical laboratory tests that use breath as the specimen

Here’s a development that reinforces two important trends in diagnostics: non-invasive clinical laboratory assays and patient-self testing. Recently, the FDA expanded the clearance of one diagnostic test to allow patients to collect their own breath specimen at home under the supervision of the test manufacturer’s telehealth team.

The C-Spirulina Gastric Emptying Breath Test (GEBT) breath test from Cairn Diagnostics initially received federal Food and Drug Administration (FDA) approval in 2015. At that time, the test was required to be administered “at a physician’s office, a laboratory collection center, or in a tertiary care setting,” according to a 2016 news release.

Recently, however, the FDA announced it has “expanded the approval of the company’s 13C-Spirulina Gastric Emptying Breath Test (GEBT) to now include ‘at home’ administration under virtual supervision of Cairn Diagnostics.”

Self-administration of at-home tests by patients guided virtually by healthcare professionals is a major advancement in telehealth. But will this virtual-healthcare method be popular with both patients and their physicians?

Clinical Laboratory Diagnostics and Telehealth

Spurring a far greater acceptance of telehealth among patients and healthcare providers is one of the many ways the COVID-19 pandemic has impacted healthcare.

“Telehealth, particularly during the COVID-19 pandemic, has emerged as a preferred option for healthcare providers,” noted Kerry Bush, President and COO of Cairn Diagnostics, in a 2021 news release

Cairn’s GEBT detects gastroparesis, a disease which, according to the NIH National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), affects 50 people in every 100,000. According to the CDC, it is also sometimes a complication of diabetes. Symptoms include nausea, heartburn, bloating, a feeling of fullness long after eating a meal, vomiting, belching, and pain in the upper abdomen, the NIDDK notes.

In people with gastroparesis—sometimes called “delayed gastric emptying”—muscles that normally move food from the stomach to the small intestine do not work as they should, and the food remains in the stomach for too long. The traditional diagnostic tool used to diagnose gastroparesis is scintigraphy. The patient consumes a meal that has radioactive material mixed in and the digestion process is observed using a nuclear medicine camera as the material is eliminated through the bowels.

Cairn Diagnostics’ C-Spirulina Gastric Emptying Breath Test

Cairn Diagnostics’ C-Spirulina Gastric Emptying Breath Test (above) recently received an expansion to its initial 2015 FDA approval that enables patients to self-administer the test at-home while being virtually guided by the company’s telehealth team. GEBTs are interpreted by CLIA-certified clinical laboratories and the results sent to patients’ doctors within 24-48 hours after testing. (Photo copyright: Cairn Diagnostics.)

Virtual Telehealth GEBT versus Scintigraphy

The telehealth process for Cairn Diagnostic’s Gastric Emptying Breath Test (GEBT) differs significantly from traditional scintigraphy testing. Once a physician prescribes the test, Cairn’s telehealth team contacts the patient to describe the virtual process. The team then ships the at-home test kit to the patient. To complete the testing, Cairn provides the patient with a web-based link to a secure audio/video platform.

During administration of the GEBT, a Cairn technician coaches the patient and supervises via video. Once the test is complete, the patient returns the breath samples to the CLIA-certified clinical laboratory by overnight courier. The test results are sent to the prescribing physician within 24-48 hours after the lab receives the samples.

Discovering New Uses for Breath as a Specimen for Clinical Laboratory Testing

For obvious reasons, patients prefer diagnostics that use specimens obtained noninvasively. GEBT is the latest in a growing list of diagnostic tests that use breath as a specimen.

For example, at Johns Hopkins clinicians employ breath testing to diagnose several conditions, including:

Each of these tests involves the patient consuming a particular substance, technicians capturing breath samples at certain intervals, and clinical laboratory personnel analyzing the samples to look for indicators of disease or intolerance.

New Types of Breath Tests

Breath samples are commonly used to diagnose gastrointestinal issues, but researchers also are seeking methods of using them to diagnose and monitor respiratory conditions as well.

In a recent study published in Nature Nanotechnology, scientists explored how breath can be used to monitor respiratory disease, noting that although breath contains numerous volatile metabolites, it is rarely used clinically because biomarkers have not been identified.

“Here we engineered breath biomarkers for respiratory disease by local delivery of protease-sensing nanoparticles to the lungs. The nanosensors shed volatile reporters upon cleavage by neutrophil elastase, an inflammation-associated protease with elevated activity in lung diseases such as bacterial infection and alpha-1 antitrypsin deficiency,” the researchers wrote.

Indeed, the search for new ways to use breath as a biological sample is being pursued by numerous groups and organizations. Owlstone Medical in the UK, for example, is developing breathalyzer tests for the detection of cancer as well as inflammatory and infectious disease.

“Exhaled breath is more than just air,” notes the company’s website. “It contains over 1,000 volatile organic compounds (VOCs) as well as microscopic aerosol particles, also known as respiratory droplets, originating from the lungs and airways.”

Analyzing breath allows for the:

  • investigation of biomarkers of disease,
  • patient stratification by phenotype,
  • detection and monitoring treatment response, and
  • measurement of exposure to harmful substances.

In fact, so many studies on using breath as a specimen have been conducted that in “Breath Biomarkers in Asthma: We’re Getting Answers, But What Are the Important Questions?” researchers Peter J. Sterk, PhD, Professor of Pulmonology at Amsterdam University Medical Centers, and immunity and respiratory medicine specialist Stephen J. Fowler, MD, FRCP, Professor of Respiratory Medicine at the University of Manchester in the UK suggested that systematic reviews are now feasible. They published their article in the European Respiratory Journal.

“Whilst we are still in this discovery stage it is time to refine our study designs so that we can make progress towards tailored clinical application,” they wrote. “Breathomics is perhaps at the ‘end of the beginning’ for asthma at least; it has a ‘sexy’ name, some promising and consistent findings, and the key questions are at least being recognized.”

Better for Patients, Clinicians, and Clinical Laboratories

Virtual telehealth tests, ordered by physicians, administered at home, and interpreted in CLIA-certified clinical laboratories, is a trend pathologists may want to watch carefully, along with the development of other tests that use human breath as the specimen. 

Less invasive, more personalized diagnostic tools that can be administered at home are better for patients. When those tools also provide detailed information, clinicians can make better decisions regarding care. Clinical laboratories that approach the use of at-home tests creatively, and which can accurately and quickly process these new types of tests, may have a market advantage and an opportunity to expand and grow.

Dava Stewart

Related Information:

Cairn Diagnostics Approved for At-Home Admin of Breath Test

Cairn Diagnostics Delivers Virtual Administration of Its Novel 13C-Spirulina Gastric Emptying Breath Test

Cairn Diagnostics Launches FDA-Approved Spirulina Gastric Emptying Breath Test for Gastroparesis

NIDDK: Definition and Facts for Gastroparesis

CDC: Diabetes and Digestion

Nuclear Medicine Gastric Emptying

Johns Hopkins: Gastroenterology and Hepatology

Nature: Engineering Synthetic Breath Biomarkers for Respiratory Disease

A Breathalyzer for Disease

Breath Biopsy—Biomarkers on Exhaled Breath

Breath Biomarkers in Asthma: We’re Getting Answers, But What Are the Important Questions?

;