3D Printing Silicone Elastomer for Patient‐Specific Wearable Pulse Oximeter

• Published in: Advanced healthcare materials 2020-08, Vol.9 (15), p.e1901735-n/a
• Main Authors: Abdollahi, Sara, Markvicka, Eric J., Majidi, Carmel, Feinberg, Adam W.
• Format: Article
• Language: English
• Subjects: 3-D printers; 3D printing; Biological properties; Blood; Cuffs; Dimensional analysis; Elastic properties; Elastomers; Embedding; health monitors; Heart rate; Humans; Hydrogels; Oximetry; Oxygen; Oxygen content; Oxygenation; Photoplethysmography; Polydimethylsiloxane; Prepolymers; Printing; Printing, Three-Dimensional; pulse oximeters; Pulse oximetry; Silicone Elastomers; Silicone resins; Silicones; soft materials; Three dimensional printing; Tissues; wearable devices; Wearable Electronic Devices; Wearable technology
• ISSN: 2192-2640; 2192-2659
• DOI: 10.1002/adhm.201901735

Commercial pulse oximeters are used clinically to measure heart rate and blood oxygen saturation and traditionally made from rigid materials. However, these devices are unsuitable for continuous monitoring due to poor fit and mechanical mismatch. Soft materials that match the elastic properties of biological tissue provide improved comfort and signal‐to‐noise but typically require molding to manufacture, limiting the speed and ease of customizing for patient‐specific anatomy. Here, freeform reversible embedding (FRE) 3D printing is used to create polydimethylsiloxane (PDMS) elastomer cuffs for use on the hand and foot. FRE enables printing liquid PDMS prepolymer in 3D geometries within a sacrificial hydrogel bath that provides support during cure. This serves as proof‐of‐concept for fabricating patient‐specific pulse oximeters with pressure sensing, termed P3‐wearable. A sizing analysis establishes dimensional accuracy of FRE‐printed PDMS compared to anatomical computer‐aided design models. The P3‐wearable successfully outputs photoplethysmography (PPG) and pressure amplitude signals wirelessly to a tablet in real time and the PPG is used to calculate heart rate, blood oxygen content, and activity state. The results establish that FRE printing of PDMS can be used to fabricate patient‐specific wearable devices and measure heart rate and blood oxygenation on par with commercial devices. A wearable pulse oximeter with pressure sensing is developed using freeform reversible embedding 3D printing of silicone elastomer. The 3D prints are based on anatomical scans of the finger or toe, resulting in patient‐specific, soft cuffs that are integrated with flexible electronics to calculate heart rate, blood oxygen content, and activity state.