Flexible electronics technology dramatically changes the capability of sensors, which allows us to detect human biological signals not only on the skin but also inside the human body. Wearable sensors that stick to the skin surface can detect various biomechanical movements, biological signals, and byproducts such as useful elements from sweat and body temperature. On the other hand, implantable sensors directly or indirectly contact with biological components inside the body, such as tissue, organs, or muscles, to support or treat bodily functions or problems. With the development of these advanced sensors, we can live together with a huge number of sensors in the future. Toward body sensor networks that can be fully implanted in the future, sustainable energy sources that support the operation of sensors as well as the development of materials that enable long-term use inside the body remain challenges. In this review, we first summarize various state-of-the-art sensors in terms of flexible and wearable platforms. Additionally, we review the recent research trends of energy harvesters in mechanical and thermal energy conversion into useful electricity for the operation of the sensors. Furthermore, we cover recent studies in the aspect of materials for implantable sensors. Finally, we discuss future direction of the sensors that may enable implanted body sensor networks in the body.I. INTRODUCTION
Team at MIT lead by Pablo Jarillo~Herrero discovered that bilayer graphene
finely tuned at precise angle 1.1 degrees turns in a supercontactor . This opened up the whole new area of investigation reffered to as twistronics with teams across the world expand on initial findings.
Rebeca Ribeiro-Palau with her team created a device where the angle between the layers can be dynamically tuned and thus presented a possibility for twistable electronics where the material properties can be changes on demand .
Xiaomeng Liu et al. reported that this setup can be further modified by application and tuning of an electric field perpendicular to the surface and inducing and in plane magnetic field that affects spin-polarized superconducting states in the graphene bilayer .
David H. Freedman, “With a Simple Twist, a ‘Magic’ Material Is Now the Big Thing in Physics“, Quanta Magazine, April 30, 2019
Allan H. MacDonald, “Trend: Bilayer Graphene’s Wicked, Twisted Road“, APS Physics, May 6, 2019
 Y. Cao et al., “Unconventional superconductivity in magic-angle graphene superlattices” Nature, vol. 556, no. 7699, pp. 43–50, Mar. 2018.
 R. Ribeiro-Palau, C. Zhang, K. Watanabe, T. Taniguchi, J. Hone, and C. R. Dean, “Twistable electronics with dynamically rotatable heterostructures” Science, vol. 361, no. 6403, pp. 690–693, Aug. 2018.
 X. Liu et al., “Spin-polarized correlated insulator and superconductor in twisted double-bilayer graphene”,Mesoscale and Nanoscale Physics, Mar 2019
Lamborghini and MIT’s graphene supercar
(a) XRD patterns
(b) and (c) SEM images
(d) Absorbance (Abs) / hν
(e) (F(R)·hν)2 / hν
(a) Fabricated hybrid energy cell, schematic (b) ZnO nanowire array grown on an ITO/PET substrate
(c) SEM image of the ZnO nanowire array
(d) Cross-section of ZnO nanowire array
Perovskites have great potential as solar cell harvesters 
KBNNO is a perovskite is a hybrid energy harvester surpassing properties of ZnO and AlN 
 Ya Yang, Hulin Zhang, Guang Zhu, Sangmin Lee, Zong-Hong Lin, and Zhong Lin Wang, Flexible Hybrid Energy Cell for Simultaneously Harvesting Thermal, Mechanical, and Solar Energies, 2013
 Yang Bai, Tuomo Siponkoski, Jani Peräntie, Heli Jantunen, and Jari Juuti Ferroelectric, pyroelectric, and piezoelectric properties of a photovoltaic perovskite oxide, 2017
Company Northrop Grumman has realized an experimental unmanned plane US Navy. The aircraft is capable of carrying 2 tons of load, has reach of 3900 km and the possibility to tank in air which extends its reach by several times. On top of that it reaches the speed no other drone can , 0.92 Ma.
Graphene nanoplatelets self-assemble into electrical contacts
Metal Halide Perovskaite Solar Cells have shown a very rapid growth in energy convesrion efficency from around 3 % in 2009 to 22.1 % reported in 2016 . Last year in August scientist at EPFL have published their work on perovskite nanowire-graphene hybrid phototransistors claiming that they have created an outstanding photodetectors . Another team of researchers from Italy have reported their perovskite-graphene solar cells to have efficiency exceeding 18 % .
 Collavini, S., Völker, S. F. and Delgado, J. L., “Understanding the Outstanding Power Conversion Efficiency of Perovskite-Based Solar Cells”. Angewandte Chemie International Edition. 54 (34): 9757–9759, (2015)
 EPFL, Graphene-perovskite hybrids make new super-detectors, Aug 06, (2015)[6,7]
 Graphene-perovskite solar cells exceed 18% efficiency, Oct 05, (2016)
 Interview from Dr. Lioz Etgar, from the Hebrew University’s perovskite lab, Nov 28, (2016)
 Spina, M., et al, Microengineered CH3NH3PbI3 Nanowire/Graphene Phototransistor for Low-Intensity Light Detection at Room Temperature, Small, 11, No. 37, 4824–4828, (2015)
 Spina, M., et al, Supporting Information to above article, (2015)