The investigators want to test in this non-randomized clinical trial a new method of administrating Pilocarpine medicine into the skin during the Sweat testing process that does not use any electrical current.

Sweat collection tests are done when a patient is suspected of having cystic fibrosis. This procedure for collection of sweat samples is called the Sweat Test and the measurement of sweat chloride concentration from the collected sweat sample is the gold standard for the diagnosis of Cystic Fibrosis.

When the sweat test is performed for patients in a hospital lab, the standard method uses a small electrical current to push pilocarpine medicine into the skin of the forearm, after which sweat is collected for testing. However, many people do not make enough sweat during this standard method of testing and have to come back for repeated testing. The investigators want to test a new method of putting Pilocarpine medicine into the skin during the Sweat testing process that does not use any electrical current.

The testing will be done once for every participant and no further follow up or additional testing is needed. The study team plans to invite healthy adults who are not taking any medicines to participate through a flyer posted in Emory Children's Center bulletin board. For those interested in participating, the study will be explained to them in detail and an informed consent will be obtained. The subjects will be asked to sit for 45 minutes on a chair as the study related procedures are completed on their arms. The right forearm will be used for pilocarpine iontophoresis method and the left forearm will be used for microneedle-based stimulation method for a period of 5 minutes. An additional microneedle control patch (without any Pilocarpine) will be placed on the left forearm to make sure that there are no skin changes from the microneedles. After the first 5 minutes, the sweat collection devices (Macroduct) will be placed on both forearms to collect sweat samples from each site. After the completion of this 30-minute collection phase, the Macroduct collectors will be removed by the study team and the subject testing will be complete. The study team will store the sweat samples to measure their chloride concentration at the end of the enrollment phase of the study.

This study will be conducted in a research room at Emory Children's Center and no compensation will be provided to the participants. At the end of the study, the research team will compare the two methods based on how much sweat was produced in each individual's arms with either of these methods. The results of this study will help to improve the current technique of sweat testing and help reduce the need for repeated testing in patients being evaluated for Cystic Fibrosis.

Inclusion Criteria:

• Age >18 years
• Signed a written informed consent
• Not taking any medications
• No known medical diagnoses or chronic conditions

Exclusion Criteria:

• Age <18 years
• Family history of Cystic Fibrosis
• History of skin disorders (eczema, psoriasis etc.) that could prevent sweat testing on forearms
• Current medication use

A total of 50 subjects provided informed consent for participation in this study. Participants had 2 different types of sweat collection method, one in each arm: the standard of care pilocarpine iontophoresis method on the left forearm and the pilocarpine microneedle patch method on the right forearm. The 50 subjects were able to undergo sweat testing on both forearms during their study visit.

All enrolled subjects were observed for a total period of 1 hour from the time consent was given and all testing and follow up evaluation completed.