Efficient heat dissipation with hybrid composite-based microfluidic heat sinks in flexible electronics

Regulating unwanted heat generation has become a significant challenge in flexible electronic devices. Traditional heat sinks are typically rigid, bulky, and designed for conventional electronics. When designing a flexible heat sink, fundamental aspects such as thermal conductivity, specific heat capacity and elasticity must be taken into consideration. In this context, we present a flexible hybrid composite material engineered using polydimethylsiloxane (PDMS), graphene oxide (GO), and paraffin wax (PW) and propose a microfluidic heat sink device with spiral microchannel fabricated employing three-dimensional printed scaffold removal method followed by casting. The PDMS composite with 5% w/w PW and 5% w/w GO exhibited improved material characteristics in terms of thermal conductivity, specific heat capacity, and elasticity, making it ideal for microfluidic device fabrication. The performance of the microfluidic heat sink device was evaluated both experimentally and numerically under a constant heater temperature of 358 K, with flow rates varying from 40 to 240 μl min⁻¹. The results demonstrated that at a relatively high flow rate of 240 μl min⁻¹, the average hotspot temperature was approximately 4.3 K lower than its PDMS counterpart, emphasizing the significant influence of material properties and channel hydrodynamics.