Self-sampling has gained significant interest over the past decade, accelerated in recent years by the Covid-19 pandemic. Clinical self-sampling has been commonplace within infectious disease applications such as sexually transmitted infections (STIs) and HPV screening. Today, due to technological advancements, remote patient self-sampling is gaining significant recognition in many clinical applications.

Today, clinical diagnostics is largely based on blood, with the standard procedure being the patient travels to the health care facility to have a venous blood draw taken by a trained phlebotomist. The demand for protecting vulnerable patients on blood monitoring programs and improving patient outcomes has fuelled the development in novel, accurate remote self-sampling solutions.

Capitainer has developed a solution based on a combination of new, advanced microfluidic technologies and traditional well established dried blood spot (DBS) techniques. The solution delivers a highly accurate volumetric sample for quantitative analytical results of the highest standard [1].

We see many demands on a sampling device for blood to be successfully implemented into clinical diagnostic pathways and have therefore built these features into our product. In this blog we would like to highlight three of them:

1: It should be impossible to leave an incorrect sample

There should be no risk or stress on the patient to ensure the sample they’ve given is correct.

The main risk we see revolves around sample volume inaccuracy when you leave it to the patient to handle the device correctly. Therefore, a device built for self-sampling must be simple for the patient to use, giving confidence in the sample volume accuracy, i.e. the device must make it impossible to over- or under-fill, every time. This is exactly how the Capitainer®qDBS device is designed.

The patented technology of the Capitainer®qDBS device involves state-of-the-art microfluidics. A microcapillary meters 10 µL of blood to a pre-cut 6mm DBS disk with any extra transferred to an excess DBS disc. Learn more about the technology and design here.

In situations where the sampler doesn’t apply enough blood, the microcapillary metering will not have enough blood to deliver the quantitative volume to the pre-cut disk. There will be no sample in the qDBS disc, not an underfilled sample.

The inbuild metering delivers absolute confidence that the device cannot be over or under filled.

2: Instant confirmation of successful sampling

We think the patient instantly must know that they have succeeded with their sampling. This eliminates uncertainty for the patient and gives confidence to themselves and the process of self-sampling.

As described above, the Capitainer technology automatically ensures that a sample on the qDBS disc is of accurate volume. In addition, we have built in the feature that the qDBS disc is visible at a control window. This means that the patient directly at home gets a confirmation showing they have succeeded with their sampling.

Successful sampling is seen at the lower spot in the image. If not enough blood is added, the qDBS disc will remain blue as the upper disc . If successful sampling is indicated, the device ensures 10µl without risk of over- or under-fill.

3: Easy to use

The device must also be easy to use with high success rate for first time users. For this, we have designed the inlet with a material that neatly guides the blood into the device. This material not only makes the device functional but look clean after sampling. All adding confidence that the patient can perform sampling professionally themselves.

Capitainer®qDBS has been extensively used with self-sampling and first time device users for SARS-CoV-2 IgG diagnostics in Sweden. When the samples arrived at the lab >95% were correct with blood filled in the qDBS disc enabling the laboratory to deliver a clinical result. We are convinced the high success rate is largely thanks to the three important points described above.

DBS has been in use since the 1960:s. However, with the limitations of conventional DBS of unknown sample volume, and haematocrit variation, clinical usage has mainly stayed within newborn screening. There are over 2000 unique analytes published using conventional DBS, nicely reviewed in a recent publication [2]. With Capitainer®qDBS these applications can now be developed into truly quantitative tests enabling them to be used for many widespread clinical diagnostic applications with self-sampling.

At Capitainer we believe in equal access to healthcare diagnostics for everyone, everywhere!

The journey towards patient centric clinical sampling has now well and truly started.

References:

N. Spooner, A. Olatunji, K. Webbley, Investigation of the effect of blood hematocrit and lipid content on the blood volume deposited by a disposable dried blood spot collection device, Journal of Pharmaceutical and Biomedical Analysis, Volume 149, 2018, Pages 419-424, ISSN 0731-7085, https://doi.org/10.1016/j.jpba.2017.11.036

Jeffrey D Freeman, Lori M Rosman, Jeremy D Ratcliff, Paul T Strickland, David R Graham, Ellen K Silbergeld, State of the Science in Dried Blood Spots, Clinical Chemistry, Volume 64, Issue 4, 1 April 2018, Pages 656–679, https://doi.org/10.1373/clinchem.2017.275966