Center for Emergent Matter Science (CEMS), RIKEN, Saitama, Japan.
Organic Materials Laboratory, Samsung Advanced Institute of Technology (SAIT), Samsung Electronics, Co., Suwon, South Korea.
Nature. 2018 Sep;561(7724):516-521. doi: 10.1038/s41586-018-0536-x. Epub 2018 Sep 26.
Next-generation biomedical devices will need to be self-powered and conformable to human skin or other tissue. Such devices would enable the accurate and continuous detection of physiological signals without the need for an external power supply or bulky connecting wires. Self-powering functionality could be provided by flexible photovoltaics that can adhere to moveable and complex three-dimensional biological tissues and skin. Ultra-flexible organic power sources that can be wrapped around an object have proven mechanical and thermal stability in long-term operation, making them potentially useful in human-compatible electronics. However, the integration of these power sources with functional electric devices including sensors has not yet been demonstrated because of their unstable output power under mechanical deformation and angular change. Also, it will be necessary to minimize high-temperature and energy-intensive processes when fabricating an integrated power source and sensor, because such processes can damage the active material of the functional device and deform the few-micrometre-thick polymeric substrates. Here we realize self-powered ultra-flexible electronic devices that can measure biometric signals with very high signal-to-noise ratios when applied to skin or other tissue. We integrated organic electrochemical transistors used as sensors with organic photovoltaic power sources on a one-micrometre-thick ultra-flexible substrate. A high-throughput room-temperature moulding process was used to form nano-grating morphologies (with a periodicity of 760 nanometres) on the charge transporting layers. This substantially increased the efficiency of the organophotovoltaics, giving a high power-conversion efficiency that reached 10.5 per cent and resulted in a high power-per-weight value of 11.46 watts per gram. The organic electrochemical transistors exhibited a transconductance of 0.8 millisiemens and fast responsivity above one kilohertz under physiological conditions, which resulted in a maximum signal-to-noise ratio of 40.02 decibels for cardiac signal detection. Our findings offer a general platform for next-generation self-powered electronics.
下一代生物医学设备将需要自供电，并能贴合人体皮肤或其他组织。这种设备将能够准确、连续地检测生理信号，而无需外部电源或笨重的连接线。自供电功能可以通过柔性光伏电池来实现，这种电池可以附着在可移动和复杂的三维生物组织和皮肤上。已经证明，超灵活的有机电源可以缠绕在物体上，在长期运行中具有机械和热稳定性，因此在与人体兼容的电子设备中具有潜在的用途。然而，由于其在机械变形和角度变化下的输出功率不稳定，这些电源与包括传感器在内的功能电子设备的集成尚未得到证明。此外，在制造集成电源和传感器时，需要将高温和高能耗工艺最小化，因为这些工艺可能会损坏功能器件的活性材料并使几微米厚的聚合物衬底变形。在这里，我们实现了自供电的超灵活电子设备，当应用于皮肤或其他组织时，这些设备可以以非常高的信噪比测量生物特征信号。我们在一微米厚的超柔性衬底上集成了用作传感器的有机电化学晶体管和有机光伏电源。采用高通量的室温成型工艺在电荷传输层上形成纳米光栅形态（周期为 760 纳米）。这大大提高了有机光伏的效率，使其功率转换效率达到 10.5%，并产生了 11.46 瓦/克的高功率/重量值。在生理条件下，有机电化学晶体管表现出 0.8 毫西门子的跨导和超过 1 千赫兹的快速响应，从而使心脏信号检测的最大信噪比达到 40.02 分贝。我们的研究结果为下一代自供电电子产品提供了一个通用平台。
