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An ultraflexible organic differential amplifier for recording electrocardiograms

Nature Electronics volume 2, pages 351–360 (2019)Cite this article

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Abstract

Differential amplifiers based on organic thin-film transistors (OTFTs) are attractive for monitoring human vital signs because of their signal amplification and noise elimination capabilities. However, substantial variations in OTFTs lead to the degradation of signal processing performance in circuits and restrict the development of organic differential amplifiers capable of recording weak physiological potentials. Here, we report a 2-μm-thick ultraflexible organic differential amplifier capable of processing physiological signals with high signal integrity and sensitivity. Our approach uses a circuit design and compensation technique that suppress the mismatch among OTFTs to less than a few percent. This leads to a common-mode noise attenuation factor below −12 dB, even during bending to ~50 μm. Using our flexible amplifier, we monitor electrocardiogram signals, where the power of 60 Hz electrical harmonic noise was reduced ~60 times during amplification, yielding electrocardiogram signals with a signal-to-noise ratio of 34 dB.

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Fig. 1: Ultraflexible signal-processing circuit with functionality on foil.
Fig. 2: Circuit strategy for a differential amplifier with p-type OTFTs.
Fig. 3: Organic differential amplifier on ultraflexible foil.
Fig. 4: PMC process for the organic differential amplifier.
Fig. 5: Electrical performance of the organic differential amplifier.
Fig. 6: ECG monitoring using an ultraflexible processing circuit on foil.

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Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.

References

  1. Xu, S. et al. Soft microfluidic assemblies of sensors, circuits and radios for the skin. Science 344, 70–74 (2014).

    Article  Google Scholar 

  2. Gao, W. et al. Fully integrated wearable sensor arrays for multiplexed in situ perspiration analysis. Nature 529, 509–514 (2016).

    Article  Google Scholar 

  3. Imani, S. et al. A wearable chemical–electrophysiological hybrid biosensing system for real-time health and fitness monitoring. Nat. Commun. 7, 11650 (2016).

    Article  Google Scholar 

  4. Jang, K.-I. et al. Self-assembled three dimensional network designs for soft electronics. Nat. Commun. 8, 15894 (2017).

    Article  Google Scholar 

  5. Khodagholy, D. et al. In vivo recordings of brain activity using organic transistors. Nat. Commun. 4, 1575 (2013).

    Article  Google Scholar 

  6. Kang, S. K. et al. Bioresorbable silicon electronic sensors for the brain. Nature 530, 71–76 (2016).

    Article  Google Scholar 

  7. Lu, L. et al. Wireless optoelectronic photometers for monitoring neuronal dynamics in the deep brain. Proc. Natl Acad. Sci. USA 115, E1374–E1383 (2018).

    Article  Google Scholar 

  8. Kim, J. et al. Stretchable silicon nanoribbon electronics for skin prosthesis. Nat. Commun. 5, 5747 (2014).

    Article  Google Scholar 

  9. Lim, S. et al. Transparent and stretchable interactive human machine interface based on patterned graphene heterostructures. Adv. Funct. Mater. 25, 375–383 (2015).

    Article  Google Scholar 

  10. Yeo, W. H. et al. Multifunctional epidermal electronics printed directly onto the skin. Adv. Mater. 25, 2773–2778 (2013).

    Article  Google Scholar 

  11. Wang, X., Gu, Y., Xiong, Z., Cui, Z. & Zhang, T. Silk-molded flexible, ultrasensitive and highly stable electronic skin for monitoring human physiological signals. Adv. Mater. 26, 1336–1342 (2013).

    Article  Google Scholar 

  12. Miyamoto, A. et al. Inflammation-free, gas-permeable, lightweight, stretchable on-skin electronics with nanomeshes. Nat. Nanotechnol. 12, 907–913 (2017).

    Article  Google Scholar 

  13. Koo, J. H. et al. Wearable electrocardiogram monitor using carbon nanotube electronics and color-tunable organic light-emitting diodes. ACS Nano 11, 10032–10041 (2017).

    Article  Google Scholar 

  14. Mannsfeld, S. C. B. et al. Highly sensitive flexible pressure sensors with microstructured rubber dielectric layers. Nat. Mater. 9, 859–864 (2010).

    Article  Google Scholar 

  15. Lipomi, D. J. et al. Skin-like pressure and strain sensors based on transparent elastic films of carbon nanotubes. Nat. Nanotechnol. 6, 788–792 (2011).

    Article  Google Scholar 

  16. Pang, C. et al. A flexible and highly sensitive strain-gauge sensor using reversible interlocking of nanofibres. Nat. Mater. 11, 795–801 (2012).

    Article  Google Scholar 

  17. Schwartz, G. et al. Flexible polymer transistors with high pressure sensitivity for application in electronic skin and health monitoring. Nat. Commun. 4, 1859 (2013).

    Article  Google Scholar 

  18. Gong, S. et al. A wearable and highly sensitive pressure sensor with ultrathin gold nanowires. Nat. Commun. 5, 3132 (2014).

    Article  Google Scholar 

  19. Hua, Q. et al. Skin-inspired highly stretchable and conformable matrix networks for multifunctional sensing. Nat. Commun. 9, 244 (2018).

    Article  Google Scholar 

  20. Lochner, C. M., Khan, Y., Pierre, A. & Arias, A. C. All-organic optoelectronic sensor for pulse oximetry. Nat. Commun. 5, 5745 (2014).

    Article  Google Scholar 

  21. Yokota, T. et al. Ultraflexible organic photonic skin. Sci. Adv. 2, e1501856 (2016).

    Article  Google Scholar 

  22. Bandodkar, A. J. et al. Tattoo-based potentiometric ion-selective sensors for epidermal pH monitoring. Analyst 138, 123–128 (2013).

    Article  Google Scholar 

  23. Yazicioglu, R. F., Merken, P., Puers, R. & Hoof, Ch. V. A 60 μW 60 nV/√Hz readout front-end for portable biopotential acquisition system. IEEE J. Solid State Circuits 42, 1100–1110 (2007).

    Article  Google Scholar 

  24. Yazicioglu, R. F. et al. A 30 μW analog signal processor ASIC for portable biopotential signal monitoring. IEEE J. Solid State Circuits 46, 209–223 (2011).

    Article  Google Scholar 

  25. Klauk, H., Zschieschang, U., Pflaum, J. & Halik, M. Ultralow-power organic complementary circuits. Nature 445, 745–748 (2007).

    Article  Google Scholar 

  26. Gelinck, G., Heremans, P., Nomoto, K. & Anthopoulos, T. D. Organic transistors in optical displays and microelectronics applications. Adv. Mater. 22, 3778–3798 (2010).

    Article  Google Scholar 

  27. Kaltenbrunner, M. et al. An ultra-lightweight design for imperceptible plastic electronics. Nature 499, 458–463 (2013).

    Article  Google Scholar 

  28. Sirringhaus, H. Organic field-effect transistors—the path beyond amorphous silicon. Adv. Mater. 26, 1319–1335 (2014).

    Article  Google Scholar 

  29. Wang, S. et al. Skin electronics from scalable fabrication of an intrinsically stretchable transistor array. Nature 555, 83–88 (2018).

    Article  Google Scholar 

  30. Fukuda, K. et al. Fully-printed high-performance organic thin-film transistors and circuitry on one-micron-thick polymer films. Nat. Commun. 5, 4147 (2014).

    Article  Google Scholar 

  31. Sekitani, T. et al. Ultraflexible organic amplifier with biocompatible gel electrodes. Nat. Commun. 7, 11425 (2016).

    Article  Google Scholar 

  32. Guerin, M. et al. High-gain fully printed organic complementary circuits on flexible plastic foils. IEEE Trans. Electron Devices 58, 3587–3593 (2011).

    Article  Google Scholar 

  33. Marien, H., Steyaert, M., Veenendaal, V. E. & Heremans, P. Analog techniques for reliable organic circuit design on foil applied to an 18 dB single-stage differential amplifier. Org. Electron. 11, 1357–1362 (2010).

    Article  Google Scholar 

  34. Marien, H., Steyaert, M. S. J., Veenendaal, V. E. & Heremans, P. A fully integrated ΔΣ ADC in organic thin-film transistor technology on flexible plastic foil. IEEE J. Solid State Circuits 46, 276–284 (2011).

    Article  Google Scholar 

  35. Maiellaro, G. et al. High-gain operational transconductance amplifiers in a printed complementary organic TFT technology on flexible foil. IEEE Trans. Circuits Syst. 60, 3117–3125 (2013).

    Article  Google Scholar 

  36. Chang, J., Zhang, X., Ge, T. & Zhou, J. Fully printed electronics on flexible substrate: high gain amplifiers and DAC. Org. Electron. 15, 701–710 (2014).

    Article  Google Scholar 

  37. Pecunia, V. et al. Trap healing for high-performance low-voltage polymer transistors and solution-based analogue amplifiers on foil. Adv. Mater. 29, 1606938 (2017).

    Article  Google Scholar 

  38. Fuketa, H. et al. 1-μm-thickness ultra-flexible and high electrode-density surface electromyogram measurement sheet with 2 V organic transistors for prosthetic hand control. IEEE Trans. Biomed. Circuits Syst. 8, 824–833 (2014).

    Article  Google Scholar 

  39. Kondo, M. et al. Ultraflexible and ultrathin polymeric gate insulator for 2 V organic transistor circuits. Appl. Phys. Express 9, 061602 (2016).

    Article  Google Scholar 

Download references

Acknowledgements

This work was supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI grant (nos. JP16H01857, JP18H01861 and JP19J22073), the New Energy and Industrial Technology Development Organization (NEDO), the Center of Innovation Program from Japan Science and Technology Agency (JST), grant from the Commissioned Research of NICT and the Brain Mapping by Integrated Neurotechnologies for Disease Studies (Brain/MINDS) project of the Japan Agency for Medical Research and Development (AMED). Part of this work was performed at the Advanced Photonics and Biosensing Open Innovation Laboratory, National Institute of Advanced Industrial Science and Technology (AIST). This work for circuit simulation and design was supported by VLSI Design and Education Center (VDEC), the University of Tokyo, in collaboration with Synopsys and Cadence Design Systems. The authors thank Nippon Kayaku Co. for supplying DNTT and Daisan Kasei Co. for high-purity parylene (diX-SR).

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Authors and Affiliations

  1. The Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka, Japan

    Masahiro Sugiyama, Takafumi Uemura, Masaya Kondo, Mihoko Akiyama, Naoko Namba, Shusuke Yoshimoto, Yuki Noda, Teppei Araki & Tsuyoshi Sekitani

  2. Graduate School of Engineering, Osaka University, Suita, Osaka, Japan

    Masahiro Sugiyama, Masaya Kondo, Teppei Araki & Tsuyoshi Sekitani

  3. Advanced Photonics and Biosensing Open Innovation Laboratory, National Institute of Advanced Industrial Science and Technology, Suita, Osaka, Japan

    Masahiro Sugiyama, Takafumi Uemura, Masaya Kondo, Naoko Namba, Teppei Araki & Tsuyoshi Sekitani

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  1. Masahiro Sugiyama
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Contributions

M.S., T.U. and T.S. conceived the concept and experiments. M.S., M.A. and S.Y. designed the circuit and conceived the process for mismatch compensation. M.S., T.U., M.K. and N.N. developed the fabrication process for OTFTs and fabricated the device. M.S. carried out all experiments for device characterization and data collection for the organic circuit, with help from T.U., M.K., M.A. and N.N. M.S. wrote the manuscript in consultation with T.U., S.Y., Y.N., T.A. and T.S. All authors commented on the manuscript.

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Correspondence to Tsuyoshi Sekitani.

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Supplementary Figs. 1–15 and Supplementary Tables 1–2.

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Sugiyama, M., Uemura, T., Kondo, M. et al. An ultraflexible organic differential amplifier for recording electrocardiograms. Nat Electron 2, 351–360 (2019). https://doi.org/10.1038/s41928-019-0283-5

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