Yoshihiro Kawahara (川原圭博) is a Professor in the Department of Electrical Engineering and Information Systems, Graduate School of Engineering The University of Tokyo.

His research interests are in the areas of Computer Networks and Ubiquitous and Mobile Computing. He is currently interested in developing energetically autonomous information communication devices. Even though wireless communication technology advances, the terminals are still tethered by power codes. He's trying to eliminate the power codes by the Energy Harvesting and the Wireless Power transmission. He's not only interested in academic research activities but also enjoyed designing new business and its field trial while joining IT startup companies.

He is a technical advisor of AgIC, Inc and SenSprout, Inc.

He received his Ph.D. in Information Communication Engineering in 2005, M.E. in 2002, and B.E. in 2000. He joined the faculty in 2005. He is a member of IEICE, IPSJ, and IEEE. He's a committee member of IEEE MTT TC-24 (RFID Technologies.) He was a visiting assistant professor at Georgia Institute of Technology and MIT Media Lab.


  • Fundamental Exercise on Programming
  • Experiments and Exercises on Electrical, Electronic, and Information and Communication (Spring and Fall)
  • Android Mobile Application Development
  • Software Programming 1
  • Computational Fabrication
  • Speculative Design

Research Projects (Selected)

Instant Inkjet Circuits

Instant Inkjet Circuit is a low cost, fast and accessible technology to support the rapid prototyping of functional electronic devices. It is able to print highly conductive traces and patterns onto rigid or flexible substrates such as paper and plastic films cheaply and quickly. In addition to providing an alternative to breadboarding and conventional printed circuits, we demon- strate how this technique readily supports large area sensors and high frequency applications such as antennas. Unlike existing methods for printing conductive patterns, conductivity emerges within a few seconds without the need for special equipment. We demonstrate that this technique is feasible using commodity inkjet printers and commercially available ink, for an initial investment of less than US$100. We believe that this technology will be of immediate appeal to researchers in the ubiquitous computing domain, since it supports the fabrication of a variety of functional electronic device prototypes.

This paper received a best paper award at Ubicomp 2013!

Energy Harvesting From ambient RF signals

In order to sense the world around us, realization of a low-cost and maintenance-free wireless sensor network system is crucial. For commercial mass production of sensing systems, all-round cost cutting methods are required. In this paper, we propose a near-perpetual networked sensing platform, which scavenges electromagnetic power from ambient Radio Frequency (RF) signals using a dipole antenna printed on a paper surface. Our ultimate goal is to realize thin and fluffy wireless sensor nodes that can be carried by the wind and cover large areas like fluttery petals of blossom. This work is conducted with very close collaboration with Georgia Institute of Technology granted by NEDO.

Energy Harvesting from Ambient RF signals

Multi-hop Wireless Power Transmission

We work on a new concept of routing electric power by wireless transfer on two-dimensional surfaces, such as floors and walls. Unlike any other existing wireless power transfer scheme, this method can deliver electric power over a wide range with minimum loss. We realize this method by using a magnetic antenna array.

Each array element can be selectively resonated with adjacent elements to deliver power without physical contact.

Multi-hop Wireless Power Transmission using Magnetic Resonance

Mobile phones and wearable sensing technologies

Almost all recent mobile phones are equipped with multiple sensors, such as cameras, GPS, and accelerometers. By exploiting the sensing features, we capture many different events and share them over the mobile network. We have developed a robust and light-weight activity recognition method using on mobile phone accelerometer, and demonstrated E-Coaching Sports wear concept as well as a calorie meter. We also focus on reduction of the battery consumption of the mobile device using compressed sensing technology, development of large scale corpus.

Monitoring Daily Energy Expenditure using a 3-Axis Accelerometer with a Low-Power Microprocessor

Peer to Peer Networking

We have proposed a fully distributed scalable Peer to Peer communication protocol for a large scale networked virtual environment such as Massive Multi-player Online Role Playing Game (MMORPG). This approach was very unique because the topology of the overlay network is optimized based on the distance in the virtual world, which makes it possible to minimize the delay between users and maximizes the scalability. Currently, we are exploring content management technologies for P2P and next generation networks.




  • JSPS Research Fellowships for Young Scientists (2004-2005)
  • IPSJ SIG UBI Best paper award (2003)
  • IEEE VTS Japan 2003 Young Researcher's Encouragement Award (2003)
  • UCS2007 Best Poster Presentation Award (2007)
  • IPSJ SIG UBI Best paper award (2006, 2007, 2008 and 2009)
  • IPSJ Dicomo 2009 excellent paper award & excellent presentation award (2009)
  • IEICE Information Network Workshop Best paper award (2010)
  • IEICE The Young Researchers' Award (2010)
  • IPSJ Dicomo 2010 excellent paper award (2010)
  • IPSJ Dicomo 2011 excellent paper award (2011)
  • ACM Ubicomp 2013 Best Paper Award (2013)
  • ACM Ubicomp 2014 Best Paper Nominee Award (2014)
  • Microsoft Research New Faculty Award (2014)



  • Ubicomp 2005 Local Arrangement Committee, Student Volunteer Chair
  • IEEE 6th International Workshop on Wearable Computing and Smart Appliances (IWSAWC 2006), Organizing Committee
  • IEEE 7th International Workshop on Wearable Computing and Smart Appliances (IWSAWC 2007), Organizing Committee (Co-chair)
  • The Seventh International Conference on Pervasive Computing (Pervasive 2009), Publicity Chair
  • IEEE IMS 2012, Workshop on wireless energy transfer and scavenging techniques, for autonomous RFID and sensors, organizer
  • ACM UbiComp 2015 Publication Chair

Program Committee

  • Fourth International Conference on Networked Sensing Systems (INSS 2007), Program Committee
  • ACM Multimedia 2007, Networking Track Program Committee
  • 6th Annual Workshop on Network and Systems Support for Games: Netgames 2007, Program Committee
  • International Symposium on Ubiquitous Computing Systems 2007, Program Committee
  • International Workshop on Peer-to-Peer Network Virtual Environments 2007 (P2P-NVE 2007), Program Committee
  • 2009 International Workshop on Network Assurance and Security Services in Ubiquitous Environments (NASSUE 2009), Program Committee
  • 9th Workshop of the Multimedia Metadata Community (WMM 2009), Program Committee
  • The Sixth International Conference on Ubiquitous Intelligence and Computing (UIC-09) (UIC2009), Program Committee
  • Eighth International Conference on Networked Sensing Systems (INSS 2008), Program Committee
  • Ninth International Conference on Networked Sensing Systems (INSS 2009), Program Committee
  • Fifth International Symposium on Ubiquitous Computing Systems (UCS 2009) Program Committee
  • KSE 2009 The First International Conference on Knowledge and Systems Engineering, Program Committee
  • 8th Annual Workshop on Network and Systems Support for Games: Netgames 2009, Program Committee
  • International Workshop on Peer-to-Peer Network Virtual Environments 2009 (P2P-NVE 2009), Program Committee
  • IEEE Radio and Wireless Symposium RWS 2010, Technical Program Committee
  • Tenth International Conference on Networked Sensing Systems (INSS 2010), Program Committee
  • The Eighth International Conference on Pervasive Computing (Pervasive 2010), Program Committee
  • PECCS 2011, Program Committee
  • INSS 2011, Program Committee
  • SAINT 2011, Program Committee
  • IEEE P2P 2011, Program Committee
  • P2P-NVE 2011, Program Committee
  • ICPADS 2011, Program Committee
  • CCNC 2011, Program Committee
  • AHSP 2011 (Ad Hoc, Sensor and P2P Workshop), Program Committee
  • FTRA WCC-WTA 2011,
  • INSS 2012, Technical Program Committee
  • SAINT 2012, Program Committee
  • IEEE RWS 2013, Program Committee
  • SENSORNETS 2013 Program Committee
  • AHSP 2013 : The 5th Ad Hoc, Sensor and P2P Networks Workshop, Program Committee
  • IEEE RWS 2014, Program Committee
  • IEEE RFID-TA 2014 Program Committee
  • ACM Ubicomp 2014 Program Committee
  • CEA2014 Program Committee, Publicity Co-Chair
  • HASCA2014 Program Committee
  • PowerMEMS 2014 Program Committee
  • IEEE Globecom 2015 Program Committee
  • ACM Ubicomp 2015 Program Committee
  • IEEE RFID-TA 2015 Program Committee
  • The 5th International Conference on the Internet of Things (IoT 2015) Program Committee


  • IEEE Pervasive Computing Magazine, Editorial Board (2015-)
  • IPSJ Transaction (2007,2009,2010,2011)
  • Transaction of IEICE (2007,2008,2009)


Ubicomp 2012, Ubicomp 2009, Pervasive 2006, Ubicomp 2005, Ubicomp 2004, IWSAWC 2007, IWSAWC 2006, IWSAWC 2005, INSS 2007, INSS 2008, ICMLC 2007 etc.


IEEE MTT-S TC-24 (RFID technologies) Committee

IEEE MTT-S TC-26 (Wireless Power Transmission) Committee