IntroductionDetermination of blood lactate levels supports decision-making in a range of medical conditions. Invasive blood-sampling and laboratory access are often required, and measurements provide a static profile at each instance. We conducted a phase I clinical study validating performance of a microneedle patch for minimally invasive, continuous lactate measurement in healthy volunteers.MethodsFive healthy adult participants wore a solid microneedle biosensor patch on their forearms and undertook aerobic exercise for 30 min. The microneedle biosensor quantifies lactate concentrations in interstitial fluid within the dermis continuously and in real-time. Outputs were captured as sensor current and compared with lactate concentrations from venous blood and microdialysis.ResultsThe biosensor was well-tolerated. Participants generated a median peak venous lactate of 9.25 mmol/L (IQR 6.73–10.71). Microdialysate concentrations of lactate closely correlated with blood. Microneedle biosensor current followed venous lactate concentrations and dynamics, with good agreement seen in all participants. There was an estimated lag-time of 5 min (IQR −4 to 11 min) between microneedle and blood lactate measurements.ConclusionThis study provides first-in-human data on use of a minimally invasive microneedle patch for continuous lactate measurement, providing dynamic monitoring. This low-cost platform offers distinct advantages to frequent blood sampling in a wide range of clinical settings, especially where access to laboratory services is limited or blood sampling is infeasible. Implementation of this technology in healthcare settings could support personalised decision-making in a variety of hospital and community settings.Trial registration numberNCT04238611.

Introduction Determination of blood lactate levels supports decision-making in a range of medical conditions. Invasive blood-sampling and laboratory access are often required, and measurements provide a static profile at each instance. We conducted a Phase I clinical study validating performance of a microneedle patch for minimally-invasive, continuous lactate measurement in healthy volunteers. Methods Five healthy adult participants wore a solid microneedle biosensor on their forearms and undertook aerobic exercise for 30 minutes. The microneedle biosensor quantifies lactate concentrations in interstitial fluid (ISF) within the dermis continuously and in real-time. Outputs were captured as sensor current and compared with lactate concentrations from venous blood and microdialysis. Results The biosensor was well-tolerated. Participants generated a median peak venous lactate of 9.25 mmol/L (Interquartile range, 6.73 to 10.71). Microdialysate concentrations of lactate closely correlated with blood. Microneedle biosensor current followed venous lactate concentrations and dynamics, with good agreement seen in all participants. There was an estimated lag-time of 5 minutes (IQR -4 to 11 minutes) between microneedle and blood lactate measurements. Conclusion This study provides first-in-human data on use of a minimally-invasive microneedle biosensor for continuous lactate measurement, providing dynamic monitoring. The platform offers distinct advantages to frequent blood sampling in a wide range of clinical settings, especially where access to laboratory services is limited or blood sampling is infeasible.

We present SPECTRA-tube (specimen transportation tube), a device that enables the dry stabilization and transportation of large volumes (>1 mL) of liquid specimens. We demonstrate its application in molecular and culture testing of tuberculosis.

Technologies for preservation of specimens in the absence of cold chains are essential for optimum utilization of existing laboratory services in the developing world. We present a prototype called specimen transportation tube (SPECTRA-tube) for the collection, exposure-free drying, ambient transportation, and liquid state recovery of large-volume (>1 mL) specimens. Specimens introduced into SPECTRA-tube are dried in glass fiber membranes, which are critical for efficient liquid-state sample recovery by rehydration and centrifugation. Mycobacterium smegmatis (Msm)-spiked mock sputum dried in native Standard 17 glass fiber was stable for molecular testing after 10-day storage at 45°C, and for culture testing after 10- and 5-day storage at 37°C and 45°C, respectively. Compatibility with human sputum storage was demonstrated by dry storing Mycobacterium bovis-spiked pooled human sputum in SPECTRA-tube for 5 days at room temperature followed by successful qPCR detection. By significantly increasing the volume of samples that can be transported in the dry state and enabling recovery of the entire sample in liquid state, SPECTRA-tube presents a potential universal solution for the preservation and transportation of liquid specimens.