We propose a flexible and wearable thermoelectric nanogenerator (FTEG) made from Bi2Te3, which allows high voltage and output power density. The proposed FTEG works as a thermopile with the end-to-end connection of 126 thermoelectric legs, and which is fabricated through magnetron sputtering Cu conductor on polyethylene terephthalate film. Bi, Te, Sb, and Se alloys are used to prepare thermoelectric materials by doping in a fixed proportion and zone melting, and nickel plating on the surface mitigates the deterioration of thermoelectric properties caused by the diffusion of Cu atoms or Cu+ ions. The thermoelectric figure of merit is stable and maintained above 0.7, up to 1.02. More flexibility is allowed by employing double sinusoidal serpentine connecting wires, and no significant property changes are observed even after being folded 200 times. When the temperature difference reaches 50 K, the output voltage of the FTEG will be no less than 520 mV, and the power density will reach 11.14 mW·cm–2. By integration of a low-power, low-threshold voltage boost circuit on the back end of the FTEG, the electronic watch with a liquid crystal display screen can be easily powered to work properly. Furthermore, the FTEG is temperature-sensitive and, thus, can be used for temperature measurement with a resolution of 0.5 K. This work may have important prospects in flexible wearable physical sensors and individualized medical care.

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Flow and stresses induced by blood flow acting on the blood cellular constituents can be represented to a certain extent by a continuum mechanics approach down to the order of the μm level. However, the molecular effects of, e.g., adhesion/aggregation bonds of blood clotting can be on the order of nm. The coupling of the disparate length and timescales between such molecular levels and macroscopic transport represents a major computational challenge. To address this challenge, a multiscale numerical approach based on discrete particle dynamics (DPD) methodology derived from molecular dynamics (MD) principles is proposed. The feasibility of the approach was firstly tested for its ability to simulate viscous flow conditions. Simulations were conducted in low Reynolds numbers flows (Re = 25-33) through constricted tubes representing blood vessels with various degrees of stenosis. Multiple discrete particles interacting with each other were simulated, with 1.24-1.36 million particles representing the flow domain and 0.4 million particles representing the vessel wall. The computation was carried out on the massive parallel supercomputer NY BlueGene/L employing NAMD-a parallel MD package for high performance computing (HPC). Typical recirculation zones were formed distal to the stenoses. The velocity profiles and recirculation zones were in excellent agreement with computational fluid dynamics (CFD) 3D Navier-Stokes viscous fluid flow simulations and with classic numerical and experimental results by YC Fung in constricted tubes. This feasibility analysis demonstrates the potential of a methodology that widely departs from a continuum approach to simulate multiscale phenomena such as flow induced blood clotting.