领域：学术论文 · 自然科学

Thermal draw of the fibre computer
The fibre draw process started with the construction of a macroscopic preform (Fig. 1b) comprising a sacrificial, stress-bearing polymethylmethacrylate (PMMA) cladding encasing an inner hollow thermoplastic cyclic olefin copolymer elastomer (ECOC) cylinder. During the draw process, the PMMA viscous fluid carried most of the tension and offered superior dimensional control, which the more rheologically complex viscoelastic fluid (ECOC) would not. Without this, the sudden transfer of tension from the elastomer to the electrodes as the preform collapses on devices leads to an asymmetric and non-conformal fibre profile near the devices. In addition, drawing the elastomer on its own under high stress would lead to molecular chain alignment, reducing the elasticity of the fibre once quenched. During the draw process, the wires with the pre-connected devices were fed into a single large channel of the preform while the dimensions were reduced to fibre size (Fig. 1b). To maintain the structural elasticity of the conductors through the draw, it is important that the helix diameter be substantially smaller than the fibre channel diameter to minimize the frictional resistance between the wires and the polymer. After the draw process, the PMMA layer was peeled away, leaving an ECOC fibre with eight encapsulated microelectronic devices separated by nearly 15 cm, connected by helically structured wires internal to the fibre (Extended Data Figs. 2 and 3). Because the size of some devices was larger than the steady-state diameter of the fibre away from the devices, which was about 1.35 mm, the channel of the fibre fully collapsed at the devices such that the devices were surrounded by a highly conformal layer of ECOC.
Tensile and flexural properties
Compared with planar approaches with anisotropic bending stiffness, this solvent-free high-speed thermal draw approach enables conformal, hermetic encapsulation of devices within fibres composed of an elastomer with more than an order of magnitude lower modulus than conventional thermoplastics28,31, providing isotropic flexibility and elasticity35. A representative tensile measurement of a section of fibre between devices (Fig. 1c) showed that breakage of the larger-diameter strain-limiting wire occurred at 6.6% strain, whereas the failure of the first electrode necessary for fibre computer functionality occurred at 67.1% strain. Similarly, a section of the fibre with an embedded device withstood 37% strain before failure (Supplementary Fig. 2). We also found that the fibres maintained functionality for more than a thousand cycles of stretching, representative of high yarn strain in conventional wearable textiles36,37,38, with further improvements in fatigue life possible through application-specific tuning of the wire helix properties (Extended Data Fig. 4).
In addition to elastic deformations, we show that the fibre computer is capable of withstanding millimetre-scale flexural deformations, which are crucial for fabric formation and knitting in particular39,40. Bending radius measurements (Fig. 1d) showed that non-device-containing segments sustained flexural stresses down to a bending radius of 0.25 mm without failure, whereas a device-containing segment sustained flexural stresses down to a bending radius of 2.38 mm before the first break of a functional electrode due to the modulus mismatch near devices. We also found that the fibre computer withstood ten machine-washing cycles with no degradation in functionality (Extended Data Fig. 5), demonstrating environmental resilience along with mechanical reliability.
Braided fibre cladding
To further improve the mechanical robustness and surface properties of the fibre computers for fabric integration, we covered the fibre computers with diagonally interlaced textile yarns using a 16-carrier braiding machine (Fig. 1b). The elasticity of the fibre was maintained during the braiding process using a tensioned core loading approach. The versatility of this method with respect to reconfiguration of the type of yarn used, number of carriers and helix pitch allowed the independent design of the mechanical and surface properties of the fibre41,42. A wide variety of yarns were used to cover the fibre computers, including polylactic acid (PLA), Kevlar, cotton and polyester (Fig. 1e,f). The tensile strength of the fibre computer varied with yarn type and denier. A fibre computer braided with 360-denier cotton yarn had a tensile strength of 49 N, whereas a fibre computer braided with 540-denier polyester yarn had a tensile strength of 146 N (Extended Data Fig. 6). Beyond improvements in tensile strength, covering the core with low-friction yarn materials, such as polyester, reduced stiction compared to bare ECOC fibres and prevented stiction to surfaces, such as knitting needles, from causing the fibre to stretch beyond its failure strain.
Fibre computer characterization
Each fibre computer consists of eight devices connected on a single I2C bus, enabling sensing, computation, storage and communication in a single fibre (Fig. 2a). Four of these devices are sensors: a photodetector, a temperature sensor, a PPG sensor, and an accelerometer, which collect information from the environment and wearer through optical, thermal and mechanical transduction (Fig. 2b). The 32-bit MCU, capable of operating at frequencies up to 96 MHz, provides both computation and storage, with an ARM Cortex-M4 processor with a floating-point unit alongside 256 KB of onboard flash memory and 96 KB of RAM. If required, the generalizability of the interposer approach also allows storage capacity to be expanded by adding downstream memory chips. We implemented two electromagnetic methods for external communications: optically through an LED and through radio-frequency signals from a BLE unit. Intrafibre communication within the system uses the I2C addressing protocol, operating at a clock speed of 100 kHz, although the MCU can drive the bus frequencies up to a maximum of 3.4 MHz for higher throughput applications. The physical architecture uses four wires allocated for I2C (data, clock, power and ground) along with an additional wire dedicated to modulating the LED for optical communications. Through the I2C interface, devices along the length of the fibre can be individually addressed by means of unique 7-bit serial addresses, enabling processor interfacing with less than a 1-ms delay between sequential reads or writes (Extended Data Fig. 5). The MCU can also be dynamically reprogrammed over I2C to target different application requirements, even after fibre integration. The I2C protocol was selected for its use of only two signal conductors, minimizing potential mechanical failure modes; other protocols, such as serial peripheral interface (SPI) and universal asynchronous receiver-transmitter (UART), may also be adopted by either adding additional conductors to the fibre or through device-to-device communications on a single interposer. For applications with more stringent timing requirements, we found that transmission through the in-fibre electrodes over device-to-device spacings can support frequencies of up to 128 MHz (Supplementary Fig. 4), allowing for the adoption of higher-speed protocols if needed.
Physiological computing demonstration
To demonstrate the sensing, processing and communication capabilities of the fibre computer in a simple application, we show that health metrics, such as heart rate measurements, can be analysed on the basis of data collected by the embedded PPG sensor in close contact with the subject’s skin using signal filtering and feature recognition techniques applied by the in-fibre processor. As PPG sensors are susceptible to motion artefact noise, we show that the in-fibre MCU is capable of applying low-pass filtering and gradient thresholding to recognize individual pulses in real time from the PPG data stream received over I2C (Fig. 2c(ii)). The timing of the pulse peaks was used to calculate the wearer’s heart rate, and the MCU relayed these real-time estimates over I2C to the in-fibre BLE node, which was able to communicate the results to any BLE-compatible display device (Fig. 2c(iii)).

Power considerations
To power the embedded devices in the fibre computer, we integrated a pin-type lithium-ion battery only 3.65 mm in diameter inside an ECOC fibre, using a lower-temperature fibre draw to prevent the temperature rise from causing battery degradation. To allow for ease of connection for power, reprogramming and charging, the fibre computers and fibre batteries were terminated with 2.5-mm tip–ring–ring–sleeve (TRRS) audio connectors that can be connected together (Supplementary Fig. 7). After the draw process, we found that the battery-embedded fibre retained a rated battery capacity of 15 mAh (Fig. 2d(i)) and remained rechargeable over multiple uses (Fig. 2d(ii)). To reduce the battery voltage to the required 3.3 V power and I2C logic levels, an in-fibre LDO voltage regulator and pull-up resistors for the I2C bus were incorporated into the fibre computers. Given the baseline average current consumption during code execution (Fig. 2d(iii)), the battery-embedded fibre was capable of powering the fibre computer for up to 6 h. The capability for high-efficiency 1C discharge also demonstrated the ability to accommodate spikes in the current draw, such as those that occur during communications (Supplementary Fig. 6).
Fabric networking
Using the fibre computer, we proceeded to create a network of fibre computers in textile fabric. We chose optical and radio-frequency communications to avoid rigid interconnects and complex wiring schemes, which do not support ad hoc networking.
Optical communications
Optical communications were enabled through the use of a light sensor and LED present in each fibre. On–off keying modulation of the LED was used with Manchester encoding to eliminate the need for a separate clock signal and provide noise tolerance (Fig. 3c). We demonstrate optical communications up to 10 kHz (Extended Data Fig. 7); higher-speed optical communications can also be implemented using higher-bandwidth photodetectors. For multi-fibre optical communications, an addressable message protocol was established. The network architecture used a two-bus topology (Fig. 3a), where LED and light sensor pairs in each fibre were coupled to those in other fibres by means of two waveguide buses, which acted to improve the bidirectional communication distance compared to free-space transmission. For fibre pairs with LEDs that are aligned on the same bus, or if the distance between fibres is too large for detection, the message must be transmitted to an intermediary fibre, which can then repeat the message to the receiving fibre. To access the guided modes of the square PMMA waveguides, light must pass directly through the ECOC–PMMA interface without escaping into air. This requires a sufficient interfacial contact area between the fibre and waveguide, which can be created by deforming the surface of the elastomeric fibre with compression of the waveguide onto the fibre (Supplementary Figs. 8 and 9). We indeed found that transmission from one fibre to another was aided by increasing the compression force (Fig. 3d), with the amount of compression necessary varying on the basis of the waveguide size (Supplementary Fig. 10). At constant compression, we found that the light propagating in the waveguide had an attenuation coefficient of 0.18–0.28 cm−1 (Supplementary Fig. 10), with losses caused by the bending of the waveguide and out-coupling to the yarns of the fabric (Fig. 3e). In the future, alternate strategies for waveguide coupling and confinement, including grating couplers43,44, low-index claddings and directional light emitters, could be explored for higher-efficiency transmission.


翻译考点：
考点1：“thermal draw”应该译为热拉制”，因为这是面料行业的主流翻译
考点2：“polyester”必须译为“聚酯纤维/涤纶”，译文取其一就可，且译文前后需保持一致
考点3：  "denier"必须译为旦/旦尼尔；丹/丹尼，译文取其一就可，且要保持译文一致性
考点4：“Power considerations”推荐译为“功率考虑”或者“功耗考虑”，因为整个段落在讲的就是电力能源的消耗，译文取其一就可，且要保持译文一致性
考点5：“Ad hoc networking 应该译为“自组织网络”，不可遗漏Ad hoc 的翻译，表示自行组织，或者临时的。
考点6：”message protocol“结合上下文应该译为“通信协议”，不可译为“消息协议”这种模糊用词
考点7：”PPG sensor“应该译为“光电容积脉搏波传感器”，首次出现时，译文应该给出全称，之后再给出简称
考点8：”I2C“的中文标准译名为 "I2C总线"，全称 "Inter-Integrated Circuit"，应该译为”集成电路间总线 或 内部集成电路总线“，译文选取一种即可，维持译文的一致性，首次出现时，译文应该给出全称，之后再给出简称
考点9：“serial peripheral interface (SPI)“应该译为译为”串行外设接口（简称 SPI接口）”首次出现时，译文应该给出全称，之后再给出简称
考点10：“universal asynchronous receiver-transmitter“应该译为”通用异步收发器（简称 UART）”，业内主流翻译
考点11：“RAM” 应该译为”随机存取存储器”，首次出现时，译文应该给出全称，之后再给出简称
考点12：“fibre computer”推荐译为“纤维计算机”或者“智能纤维计算机”，选取一种即可，保持译文一致性