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Throughout the development of our project, we carefully considered its application in hospitals, and eventually nursing homes. Our device has two intended purposes:
- Continuously monitoring patients after surgeries and in ICUs in order to see if the levels of sepsis-related biomarkers increase, indicating a higher risk of sepsis occurrence in the patient.
- The sleeve will be applied to the patient’s forearm as soon as they exit the operation room, allowing for continuous monitoring of the patient throughout their recovery period.
- However, this implementation is not our primary application of the aptasensor, since one of our big goals is to be able to monitor a patient’s condition over time. Post surgical patients provide a more controlled setting as well as time of monitoring right after surgery, which is expected to provide more accurate results.
Thus, our proposed users are adult patients located in the ICU, after surgeries, or simply coming to the ER with a very high fever or other inflammatory conditions. We met with the directors of nursing and operations of the Intensive Care Unit at the Strong Memorial Hospital and they confirmed that making our device as easy to use as possible is the way to go. This means having a clear handout for nurses on how to put the sleeve on, for how long to keep it on, and how to collect the data, is important.
Instructions Outline for Aptasensor Use:
- Unwrap the sleeve device.
- Insert the sensors into the sleeve device.
- Clean the patient’s forearm with sanitary wipes.
- Apply the sleeve to the patient's forearm and tighten to the extent needed. Make sure to put the sleeve as soon after surgery as possible.
- Plug the device into the software to enable readout of the data.
- Keep the aptasensor on patients for as long as deemed necessary by medical professionals, until there is no concern for a development of immune reaction to an infection.
- Take the aptasensor off and clean with autoclave to make sure no germs are left on the sleeve.
To implement our project, we need a safe method of locally stimulating sweat that is easily implemented into the design of our device. Iontophoresis is a current method used to induce sweat when testing for cystic fibrosis, for example.1 However, this method only induces sweat for about 30-60 minutes and thus would mean for us that we would have to repeatedly induce sweat in our patients.2 This is not optimal and thus one of our main future directions is to find a more sustainable and long-lasting method of inducing sweat, without risking irritating the skin too much by the frequent stimulation. We met with several professionals, such as Dr. Fatima, who are working on a cream solution that locally induces sweat for around 2 hours, which once proved to work could be a great alternative and much easier to apply. Other options could include an automated iontophoresis device that is integrated into our current microfluidic device for the collection of sweat.
We also need to consider that individuals would require a different sleeve size, in order to properly collect sweat, as the microfluidic device needs to be in close and stable contact with the skin. For this reason, our sleeve is adjustable for pediatric and bariatric patients. The core of the aptasensor device is completely reusable after sanitization. However, we did not determine the exact lifetime of our biosensor, as the DNA aptamers might degrade in the sweat environment over time. For now, we recommend the users to replace the aptamers after using the device once.
Patients of Choice
We also recommend the aptasensor be applied to post-surgical patients. Currently, our device requires a separate software and wire connections. However, after speaking with Dr. Barbash, we realized that our current device design will be a hazard for the ED setting, which is often more fast-paced and chaotic. The safe implementation of our aptasensor into the ED setting is part of our future directions, which we hope to accomplish partially through a Bluetooth adaptation of the software. This modification, which is already being utilized in hospitals, will decrease unnecessary chords in the emergency room and will allow medical professionals to track a patient’s condition remotely.
Although our device still needs much work to be thought of as an approved and commercially available diagnostic for sepsis, throughout the past months of work we have made great progress and were able to build a prototype encompassing the most important components of what we envision our device to be like. As described on our proof of concept page we were able to produce rGO and drop cast it onto our screen-printed electrodes. We were then able to attach our sepsis biomarker-specific aptamers to the rGO which could then measure the presence of our biomarkers with our self-built potentiostat. We optimized our microfluidic device to be able to collect sweat and transport it at the required velocities to our electrodes and finally assembled all individual components together into a sleeve-like device that can be worn on the forearm or thanks to adjustable velcro on other parts of the body. If further improved, and incorporating the future directions mentioned above, we are confident that our device could bring us a great step closer to being able to diagnose sepsis earlier and thus reduce fatalities drastically. Starting with post-surgical and ICU patients at risk of developing sepsis, and then adapting the device for the emergency room to identify incoming septic patients, our device can be implemented and used easily by nurses and caregivers.
- Gokdemir, Y., and Karadag, B. T. (2021) Sweat testing and recent advances. Frontiers in Pediatrics 9.
- Davis, S. L.; Wilson, T. E.; Vener, J. M.; Crandall, C. G.; Petajan, J. H.; White, A. T. Pilocarpine-Induced Sweat Gland Function in Individuals with Multiple Sclerosis. Journal of Applied Physiology 2005, 98 (5), 1740–1744.