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Device Technologies and Biomedical Robotics

Device Technologies and Biomedical Robotics - Poster Session D

Poster I19 - PreSlice: Design of a Novel Depth-Guided Skin Biopsy Device

Friday, October 25, 2024
3:30 PM – 4:30 PM EST
Location: Exhibit Hall E, F & G

Introduction:  Of all forms of skin cancer, Melanoma is the deadliest. Cancerous melanocytes metastasize in as few as 6 weeks and thus patients are advised to obtain a timely biopsy if a suspicious skin lesion, called a dysplastic nevus, is identified. The rapid pace of melanoma growth means that an accurate and timely skin biopsy is vital for patient health and survival. Furthermore, an imprecise initial biopsy, called a “transection,” results in incorrect staging of the cancer, an irreversible mistake. Skin biopsies of dysplastic nevi can be performed via either excisional biopsy or shave biopsy; Clinicians disapprove of excisional biopsies due to cost constraints, low clinician comfort, patient cosmetic damage, and increased time and induced bleeding, so shave biopsies are preferred. However, because shave biopsies have no depth control mechanisms, the risk of transection is highly and dangerously increased. The lack of a medical standard for assessing and correcting biopsies post-transection balloons the chance of patient morbidity. We envision a novel device to increase skin biopsy precision by incorporating standardized depth control into the shave biopsy process. With a standardized depth barrier that extracts biopsies at a depth of 2 mm, PreSlice will allow dermatologists to remove the totality of a dysplastic nevus, reducing the number of transections and ameliorating the clinical diagnosis workflow for skin cancers. PreSlice will eliminate healthcare costs associated with secondary biopsies and prevent clinical ambiguity in patient treatment caused by staging inaccuracy.

Materials and

Methods:  Skin Biopsy Models
Four skin models—eggplant, tomato, pork skin, and a silicone biopsy training kit (Nasco Healthcare; Ulster County, New York)—were used to test the efficacy of PreSlice prototypes, as these mock models are commonly used to mimic the three layers the human skin (dermis, epidermis, and subcutaneous fat) for dermatological procedures (Table 1).

Testing Setup
Tests were conducted using each model mentioned above to increase confidence in the efficacy of PreSlice compared to the DermaBlade, the benchmark for shave biopsies. Testing was also performed to validate the effectiveness of PreSlice’s cork handles for improving ergonomics. Validation tests were performed at the Johns Hopkins Hospital by dermatologists with professional experience operating the DermaBlade.

Procedure and Measurement
Before each trial, a flat testing surface was sanitized. The skin model was then placed on the surface. For pork skin, the skin was pinned on a stable, sturdy material, specifically a cardboard square, using a set of push pins to fix the skin model in place. All tests were performed by creating a sawing motion with the device to enter the skin. Biopsies were conducted on all available devices to evaluate repeatability and precision. A caliper was used to measure the depth of excised samples. Time of biopsy was recorded via stopwatch.

Results, Conclusions, and Discussions: Results
When tested by non-clinicians, PreSlice devices fitted with a handle showed enhanced precision for mock biopsies performed on pork skin, tomato, and eggplant (Figure 1). Addition of the handle also demonstrated increased accuracy of PreSlice for a 2 mm excision. Furthermore, the time elapsed yielded from biopsies performed with PreSlice on both eggplant and pork skin were well under 30 seconds, fitting within the requirement for integration into the clinical workflow. Clinician testing of the PreSlice device with handle exhibited no noticeable advantage over the DermaBlade in terms of precision of depth extracted. The DermaBlade showed superior accuracy for a 2 mm depth when tested on tomatoes (Figure 2A-B), though there is no standardized depth guide for the DermaBlade. Both the DermaBlade and PreSlice with handle were unable to accurately or precisely excise samples at a depth of 2 mm from the biopsy simulation kit or eggplants (Figure 2C). Clinician testing on eggplant also showed operator variability between both PreSlice and DermaBlade. Shapes of the samples excised using the PreSlice with handle were also noticeably more oblong and irregular than those extracted via DermaBlade (Figure 2D-E), with the breadth more inconsistent visually.

Discussion
We validated PreSlice’s design iteratively by testing on silicone skin models, porcine skin, and fruit/vegetable peels, and verified PreSlice’s design via Johns Hopkins Clinicians Elise Ng, Kristin Bibee, and Jaroslaw Jedrych. We have applied for IRBs to test on human skin samples and to obtain publishable survey data from clinical residents regarding PreSlice. We are now conducting a clinical study on the usability and comfort of our design through Johns Hopkins School of Medicine, where we are receiving user feedback from dermatologists, and a cadaver study. Future prototyping will focus on evolving production from 3D printing to polymer solution casting. PreSlice provides a proof-of-concept device and mechanism to improve the precision of skin biopsies performed at 2 mm. The addition of an ergonomic handle enables PreSlice to improve operator ergonomics and standardize the motion of biopsy while maintaining low costs and demonstrating a low burden of time conducive for the clinical workflow.

Acknowledgements (Optional):  We would like to thank the Johns Hopkins University BME Department, Michelle Zwernemann, and Dr. Elise Ng.