Flexible Electronics past

break

Flexible reflectance oximeter array (Arias group)

Flexible and Wearable Electronics

break

break

Past Achievements

break

A. Wearable Electronics for Sweat Monitoring

The Javey group used its expertise in microfluidics to design and fabricate wearable electronic patches for continuous sweat monitoring at rest.3 The microfluidic design was optimized to combat evaporation, enable selective monitoring of secretion rate, and reduce required sweat accumulation times. In fact, the group developed a wearable device for rapid uptake of nL min−1 cm−2 rates of thermoregulatory sweat at rest, enabling near-real-time sweat rate and composition analysis at rest (Figure 1). Along with sweat rate sensors, the team also integrated electrochemical sensors for pH, chloride ion, and levodopa monitoring. They demonstrate patch functionality for dynamic sweat analysis related to routine activities, stress events, hypoglycemia-induced sweating, and Parkinson’s disease, thus enabling continuous, autonomous monitoring of body physiology at rest. More generally, the developed patch can be used to study correlations between sweat rates and composition, helping to better understand analyte secretion mechanisms and guide how measured concentrations should be interpreted. Recently, the group also presented wearable sweat sensors with convenient glove-based form factors for sweat sensing under routine and even sedentary activity, making sweat-based biomarker monitoring practical for daily life.4

Figure 1. Schematic of the microfluidic sweat analysis patch containing multiple layers (a) and a hydrophilic filler to enhance sweat collection (b). An optical image of the sweat patch on a user’s finger (c), or worn on various body locations (d), while continuously monitor both sweat secretion rate and compositions for long-term without external sweat stimulation (e).

break

B. Growth of Single-Crystal Semiconductors on Flexible Substrates

A flexible electronics breakthrough was recently reported by the Javey group by introducing a templated liquid-phase (TLP) crystal growth method, which enables direct growth of shape-controlled single-crystal III-Vs and group VI elements on amorphous substrates.5, 6 More importantly, growth of single-crystalline InP was demonstrated at substrate temperatures as low as 220 °C on low thermal budget substrates such as plastics and indium-tin-oxide (ITO)–coated glass (Figure 2).

Figure 2. As-grown InP on ITO-coated glass (left), and peeled polyimide (right).

break

C. Electronic Skin by Mechanotransduction

The Arias group is developing various device fabrication methods based on roll-to-roll printing (screen and inkjet printing), blade coating, and organic binding techniques. For example, the team developed printed flexible composite Zn/MnO2 batteries using organic gels as binder for the MnO2 electrode.7 Recently, the group also introduced fully flexible ambient light pulse oximeters from new organic photodiodes compatible with roll-to-roll printing techniques.8 These new wearable devices can be combined with wireless data transmission capability. They demonstrated that these flexible devices accurately detect varying oxygen saturation levels in the body.

Inspired by the skin’s sensory behavior, the Arias group developed a potentiometric mechanotransduction mechanism, which allows to encode mechanical stimuli into potential differences measured between two electrodes.9 The devices were fabricated by an all-solution processing technique and exhibited ultralow-power consumption, high tunability, and a good capability to detect both static and low-frequency dynamic mechanical stimuli (Figure 3). Based on this potentiometric sensing mechanism, the group introduced two novel devices: (i) stretchable mechanical sensors with strain-independent performance and (ii) single-electrode-mode e-skins with better pixel density and data acquisition speed compared with traditional dual-electrode-mode e-skins. This mechanotransduction mechanism has broad impact on robotics, prosthetics, and health care by providing a much-improved human-machine interface.

Figure 3. Schematic illustrations of the mechanotransducers with sandwich structure (A), side-by-side electrode configuration (B), and the all-solution processing approach (D). Picture of a microstructured ionic composite film attached on a PET substrate (E), and an optical micrograph showing the created microstructure on the surface of the ionic composite via a mesh-molding strategy (G). Scale bar: 0.5 mm

break

References

  1. Y. Yu, H.Y.Y. Nyein, W. Gao, and A. Javey, “Flexible Electrochemical Bioelectronics: The Rise of In Situ Bioanalysis,” Advanced Materials, vol. 32, pp. 1902083, Apr 2020.
  2. Y. Khan, A. Thielens, S. Muin, J. Ting, C. Baumbauer, and A.C. Arias, “A New Frontier of Printed Electronics: Flexible Hybrid Electronics,” Advanced Materials, vol. 32, pp. 1905279, Apr 2020.
  3. H.Y.Y. Nyein, M. Bariya, B. Tran, C.H. Ahn, B.J. Brown, W. Ji, N. Davis, and A. Javey, “A Wearable Patch for Continuous Analysis of Thermoregulatory Sweat at Rest,” Nature Communications, vol. 12, pp. 1823, Mar 2021.
  4. M. Bariya, L. Li, R. Ghattamaneni, C.H. Ahn, H.Y.Y. Nyein, L.-C. Tai, and A. Javey, “Glove-Based Sensors for Multimodal Monitoring of Natural Sweat,” Science Advances, vol. 6, pp. eabb8308, Aug 2020.
  5. M. Hettick, H. Li, D.H. Lien, M. Yeh, T.Y. Yang, M. Amani, N. Gupta, D.C. Chrzan, Y.-L. Chueh, and A. Javey, “Shape-Controlled Single-Crystal Growth of InP at Low Temperatures Down to 220 °C,“ Proceedings of the National Academy of Sciences, vol. 117, pp. 902-906, Jan 2020.
  6. C. Zhao, C. Tan, D.H. Lien, X. Song, M. Amani, M. Hettick, H.Y.Y. Nyein, Z. Yuan, L. Li, M.C. Scott, and A. Javey, “Evaporated Tellurium Thin Films for p-type Field-Effect Transistors and Circuits,” Nature Nanotechnology, vol. 15, pp. 53-58, Jan 2020.
  7. A.M. Zamarayeva, A. Jegraj, A. Toor, V.I. Pister, C. Chang, A. Chou, J.W. Evans, and A.C. Arias, “Electrode Composite for Flexible Zinc–Manganese Dioxide Batteries through In Situ Polymerization of Polymer Hydrogel,” Energy Technology, vol. 8, pp. 1901165, Mar 2020.
  8. D. Han, Y. Khan, J. Ting, J. Zhu, C. Combe, A. Wadsworth, I. McCulloch, and A.C. Arias, “Pulse Oximetry Using Organic Optoelectronics under Ambient Light,” Advanced Materials Technologies, vol. 5, pp. 1901122, May 2020.
  9. X. Wu, M. Ahmed, Y. Khan, M.E. Payne, J. Zhu, C. Lu, J.W. Evans, and A.C. Arias, “A Potentiometric Mechanotransduction Mechanism for Novel Electronic Skins,” Science Advances, vol. 6, pp. eaba1062, Jul 2020.