Critical Design Considerations for Longer-Term Wear and Comfort of On-Body Medical Devices

Abstract

The commercialization of a growing number of wearable devices has been enabled within recent years due to the availability of miniaturized sensor modalities, the development of new materials, and the scalability of flexible electronics. With the increase in resource shortages within healthcare, there is a demand to translate wearable devices from the commercial consumer stand-point to the medical field. Clinical-grade signal quality, wearability, and comfort all need to be tailored to a wearable design. Wear and comfort for user compliance and durability for longer-term use are commonly overlooked. In this study, the relationship of on-body location and material layer composition is investigated. Five non-woven medical tapes noted for longer wear time are tested over a 7-day timeframe. The impact of material properties, such as elasticity, isotropy, and hysteresis, as well as the moisture vapor transmission rate (MVTR) and adhesive thickness, are evaluated in relation to skin properties on the lower torso of 30, high-activity-level volunteers. User perception was quantified via Likert-scale questionnaires and images were obtained for the material-skin interaction. The results indicate that critical characteristics, such as MVTR and elasticity, noted for positive skin interaction in commercial products, may not translate to improved user perception and durability over time. Future work will assess new design options to manipulate material properties for improved wear and comfort.

Keywords: MVTR; higher activity; non-woven tapes; skin-based wearable devices; user perception; wear and comfort.

Figure 1

Images of the vital sign research platform: the (a) overall image of the wearable device; (b) description of the layers that comprised the vital sign research platform within the study, and the non-printed configuration consisted of the carrier material and skin adhesive, and the printed configuration consisted of all layers except read-out electronics; (c) dimensions of the wearable device; (d) wearable device showing placement of circuitry and sensors within the device; (e) placement indicated by blue stars for the location of wearable devices either with or without flexible circuitry incorporated on the volunteer torso’s as applied in this report.

Figure 2

Diagrams to illustrate the (a) process flow of actions required by volunteers within the study, (b) question areas asked at the beginning of the volunteer study, and (c) question areas covered during the volunteer study.

Figure 2

Diagrams to illustrate the (a) process flow of actions required by volunteers within the study, (b) question areas asked at the beginning of the volunteer study, and (c) question areas covered during the volunteer study.

Figure 3

Graphs to indicate the baseline volunteer study population and previous experience with skin reactions: (a) the pie chart noting the gender distribution within the study; (b) the pie chart to note volunteer perceived skin dryness; (c) the bar graph to note volunteers’ perception of their skin sensitivity; and (d) the bar graph to note the volunteers’ perception for the duration of the skin reaction.

Figure 4

The bar graph to show the mechanical properties of non-woven tape material within the study (A–E) for Young’s Modulus and residual strain.

Figure 5

Graphs to show patch durability over 7-day timeframe: (a) bar graph to show patch group adherence percentage for printed and non-printed configurations on volunteers; (b) box plot to show user perception of adhesive performance for printed patch configurations; (c) box plot to show user perception of adhesive performance for non-printed patch configurations.

Figure 6

Graphs to show patch awareness and overall experience over 7-day timeframe: (a) box plot to show user perception of patch awareness for printed patch configurations, (b) box plot to show user perception of patch awareness for non-printed patch configurations, (c) box plot to show user perception of overall experience for printed patch configurations, (d) box plot to show user perception of overall experience for non-printed patch configurations.

Figure 7

Box plots to show user perception for comfort and wear for printed (left column) and non-printed (right column) design configurations over the 7-day timeframe: (a,b) itchiness, (c,d) tightness, (e,f) stinging or prickling, (g,h) redness or rash.

Figure 8

Box plots to show user perception for perceived itchiness for printed configurations over the 7-day timeframe: (a) Group A, (b) Group B, (c) Group C, (d) Group d, and (e) Group E.

Figure 9

Box plots to show user perception for perceived tightness for printed configurations over the 7-day timeframe: (a) Group A, (b) Group B, (c) Group C, (d) Group d, and (e) Group E.

Figure 10

Images to show the worst-case scenario for the printed configuration of Groups A to E over the 7-day timeframe. The results are color-coded with green: intact device, orange: compromised device, and red: patch failure. The gradation in color for orange indicates an increased deterioration of the patch.

Figure 11

Images to show the worst-case scenario for the non-printed configuration of Groups A to E over the 7-day timeframe. The results are color-coded with green: intact device, orange: compromised device, and red: patch failure. The gradation in color for orange indicates an increased deterioration of the patch.