Improving the integration of e-textile microsystems' encapsulation by modifying PDMS formulation

Electronic Textiles (e-textiles) enhance traditional fabrics with electronic functionality. When embedded into textiles, flexible electronic circuits need to have reliable functionality but also survive within a textile once it has been integrated. For this, electronic microsystems would be expected by consumers and manufacturers to not alter the typical characteristics the textile inherently has - such as its washability, durability, and manufacturability. Therefore, the choice of packaging substrate for microsystems in a textile must also be hydrophobic and offer minimal expansion when washed; ensuring electronics are undetectable when the textile is handled or cleaned. This paper addresses this by using polydimethylsiloxane (PDMS) as packaging encapsulation and tailoring its fabrication method specifically for textile integration. PDMS of five different base/curing agent mixing ratios were investigated - 5:1, 7:1, 10:1, 15:1, and 20:1. Contact angle measurements and swelling tests with room-temperature distilled water, tap water, detergent, and fabric conditioner solutions show PDMS as a suitable elastomeric encapsulation for electronic textile and wearable applications. Results show that a 20:1, rather than the typical 10:1, mixing ratio offers greater aqueous resistance at smaller dimensions. Having 20:1 compared to 10:1 can reduce swelling by approximately 48% - 45% in water making it more compatible with washing.