Vol.2, January 2023

ContentsNews■ UEC signs a general agreement with Indian Institute of Technology, Varanasi.

Research Highlights：Innovation
 Meteorology
Precipitation on the radar

Video Profiles：Research Bioelectromagnetics : interaction between human body and electromagnetic waves

Video Profiles：Innovation
 Soft robotic devices: artificial muscles and soft materials for robotic applications

The University of Electro-Communications 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585© 2023 The University of Electro-Communications.

Vol.2, January 2023

NewsUEC signs a general agreement with Indian Institute of Technology, Varanasi.
UEC signs a general agreement with Indian Institute of Technology, Varanasi.
On October 4 2022, the University of Electro‐Communications（UEC）signed a general agreementwith Indian Institute of Technology, Varanasi （ IIT‐BHU ） to promote further international
collaboration.
The signing ceremony was held online and attended by UEC President Tano, Director Abe from theBoard of Directors, and three other UEC members. The ceremony began with the opening remarks byPresident Pramod Kumar Jain of IIT‐BHU and President Tano.
The signed agreements were presented after the introduction of the two universities.
Following the signing ceremony, the members of IIT‐BHU and UEC exchanged ideas for further
research and student exchange.
Indian Institute of Technology, Varanasi, is one of India's 23 national universities specializing inengineering, science, and technology. Although the entrance examinations are unified, each school
operates with its own autonomous organization. They are research institutions of national
importance and are internationally recognized for their high level of research.

President Pramod Kumar Jain（left）and President Tano（right）.

The University of Electro-Communications 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585© 2023 The University of Electro-Communications.

Vol.2, January 2023

Research Highlights：Innovation

Meteorology Precipitation on the radar

Weather radars are important instruments for measuring precipitation. Traditional radars are basedon a parabolic dish antenna. Mechanically rotating and tilting such an antenna takes a relatively
long time, and as a result, parabolic‐type radars can typically only perform sparse observations. So‐
called phased array weather radars (PAWRs) can obtain data with better spatial resolution much faster,
as they consist of an array of smaller antennas that do not require to be moved. Hiroshi Kikuchi
from the University of Electro‐Communications, Tokyo, and colleagues have now analysed theperformance of a next‐generation PAWR based in Japan: the X‐Band Dual Polarized PAWR (DP‐DAWR),
installed in 2017 at Saitama University. Specifically, they assessed the instrument’s accuracy of
precipitation measurements by comparing with data obtained from a disdrometer (a device used formeasuring raindrop sizes and velocities).
The Saitama University DP‐DAWR simultaneously transmits fan‐shaped beam pulses of horizontallyand vertically polarized radiation at 9.425 GHz, which is in the so‐called X‐Band (8 – 12 GHz). The
dual polarization improves the accuracy of precipitation amount measurements. In research mode,
the instrument has a range of 60 km and the shortest temporal resolution is 10 seconds.
Measurements during a rainstorm demonstrated that the DP‐DAWR can capture heavy rain at hightemporal and spatial resolutions. This is useful in the context of monitoring and anticipating
weather disasters in Japan such as flash flood events that are caused by locally generated heavy rain.
To quantify the accuracy of the performance of the radar, Kikuchi and colleagues compared
observational data with radar variables derived from disdrometer data. The particle size andvelocity (Parsivel) disdrometer used for this purpose is located 32 km away from the DP‐DAWR, andprovides raindrop size and speed distributions (32 size and 32 speed ranges are distinguished,resulting in 1024 raindrop types). From the disdrometer data, radar variables including the radarreflectivity factor could be calculated and compared to the observations made with the DP‐DAWR.
The comparison led to values for the mean and standard average of the radar reflectivity factor, avaluable characterization of the instrument’s accuracy.
Finally, the researchers studied a thunderstorm event, and could conclude that the DP‐PAWR is aconvenient tool for observing the rapid growth of local convective thunderstorms, occurring often inJapan. Looking forward, Kikuchi and colleagues point out that in the near future, “quantitativeevaluations of the DP‐PAWR will be conducted using other precipitation types” and that in addition,“it is necessary to improve the signal processing for the high‐reflectivity area near the edges of thedifferent fan beams”.
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Vol.2, January 2023

[Fig.1a from the paper]Photograph of the DP‐PAWR.

Hiroshi Kikuchi , Taku Suezawa, Tomoo Ushio, Nobuhiro Takahashi ,Hiroshi Hanado, Katsuhiro
Nakagawa, Masahiko Osada, Tsuyoshi Maesaka, Koyuru Iwanami, Kazuhiro Yoshimi, Fumihiko
Mizutani, Masakazu Wada and Yasuhide Hobara, Initial Observations for Precipitation Cores With X‐
Band Dual Polarized Phased Array Weather Radar, IEEE Transactions on Geoscience and RemoteSensing 58, 3657‐3666 (2020).
URL: https://ieeexplore.ieee.org/document/8949744
DOI: 10.1109/TGRS.2019.2959628
Related publications
Hiroshi Kikuchi, Yasuhide Hobara, Tomoo Ushio, Compressive Sensing to Reduce the Number ofElements in a Linear Antenna Array With a Phased Array Weather Radar, IEEE Transactions onGeoscience and Remote Sensing 60, (2022).
DOI: 10.1109/TGRS.2022.3152998

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Vol.2, January 2023

Video Profile：Research

Bioelectromagnetics : interaction between human body and electromagnetic waves
Dairoku Muramatsu
Associate Professor at the Department of Mechanical and Intelligent Systems Engineering
Dairoku Muramatsu’s research integrates electronics and bionics in an area known as“bioelectromagnetics”. “The human bodies is composed of many biological tissues, such as skin,muscle, fat, bone, and different types of organs,” explains Muramatsu. “These tissues and organs areelectrically unique materials that interact with electromagnetic waves in a complex manner. The goalof my research is to clarify this complex interaction and utilize it for communication with digitalgadgets, medical and healthcare devices, human interfaces, and even for food industry.”
In this video, Muramatsu describes two specific applications in the areas of wireless communicationand healthcare.
Human body communication is one of the areas of wireless communication technologies. Amazingly,
it is possible to use human bodies as signal transmission paths for sending digital data. Once anelectrical signal goes inside the body via electrodes, the signal propagates mainly through the humanbody and the space around the body.
The animation in the video illustrates how the electric field is distributed around the human bodywhen a radio frequency signal is excited at the wrist. Notably, the electric field is distributed onlyaround the body and propagates along the body's surface. This communication principle enables both
highly secure and low‐power communications.
As an application example of human body communication, Muramatsu implemented an LED color
control system where a user selects color information from an app on a smartphone. This informationis sent to the transmitter and modulated to a radio frequency signal. The signal is input to the handthrough the electrode and subsequently distributed as an electric field around the user’s body asdescribed above. The receiver detects the electric field as a radio frequency signal, which isdemodulated and used to control the color of the LEDs. “The important point is that the informationis transmitted only when the user directly touches the transceiver electrodes,” says Muramatsu. “So,
human body communication can be used as an intuitive touch interface in e‐money transactions, suchas a using railway networks.
In the medical healthcare field, Muramatsu is working on non‐invasive blood glucose monitoring. The
current number of diabetic patients around the world is over 500 million, and that is estimated to700 million in the next 20 years. Daily monitoring of blood glucose is vital for managing diabetes toThe University of Electro-Communications 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585© 2023 The University of Electro-Communications.

Vol.2, January 2023

prevent serious complications. The current monitoring method requires invasive blood sampling froma patient's fingertip. However, blood sampling with needle puncturing is uncomfortable, vulnerable
to infection, and can be high in cost of consumables. To address such drawbacks and to improve
patients’ quality of life, Muramatsu proposed a non‐invasive blood glucose monitoring based onbioelectromagnetics.
“Our method utilizes changes in a patient’s bioimpedance as an indicator of blood‐glucose
concentration,” says Muramatsu. “Patients put a wearable device such as a smart watch on the wrist
and the device inputs electricity to the patient’s body, and detects the bioimpedance from the sensing
electrodes on its backside. Then, we estimate the blood glucose level from the patient’sbioimpedance. In this way, we can realize non‐invasive monitoring without blood samples, infection
risk, and any consumables.”These were two examples of bioelectromagnetics. It is a multidisciplinary area of research that uses
complex human‐electricity interaction to develop practical applications that would not be possible
through engineering alone.
“We need the cooperation of researchers in a wide range of expertise,” says Muramatsu. “So, we arealways open to collaboration and exchange.”
References and further information
1. D. Muramatsu, K. Arai, K. Higuchi, “A Study on Floor Ground Contribution in Semi‐Passive Human
Body Communication”, IEICE Commun. Express, Vol.11, pp.39‐45, 2022.
https://doi.org/10.1587/comex.2021XBL0178
2. R. Takamatsu, K. Higuchi, T. Suzuki, D. Muramatsu, “Electrical Properties of Fresh Human Blood
at 10 kHz–100 MHz”, IEEJ Trans. Electr. Electron. Eng., Vol.17, No.4, pp.614‐616, 2022.
https://doi.org/10.1002/tee.23549
3. D. Muramatsu, K. Sasaki, “Noise Reduction Using a Triple‐layer Electrode in
Conductive/Capacitive Hybrid Electrocardiogram Measurement”, Sens. Mater., Vol.33, pp.4105‐
4111, 2021.
https://doi.org/10.18494/SAM.2021.3591
D. Muramatsu, “NaCl‐Based Blood Phantom Analysis for In Vitro Bioimpedance Measurement”,
AIP Advances, Vol.11, No.8, pp.1‐5, 2021.
https://doi.org/10.1063/5.0055949
4. D. Muramatsu, K. Sasaki, “Transmission Analysis in Human Body Communication for Head‐Mounted Wearable Devices”, Electronics, Vol.10, No.10, pp.1213‐1227, 2021.
https://doi.org/10.3390/electronics10101213
5. Y. Nishida, K. Sasaki, K. Yamamoto, D. Muramatsu, F. Koshiji, “Equivalent Circuit Model Viewed
from Receiver Side in Human Body Communication”, IEEE Trans. Biomed. Circ. Sys., Vol.13, No.4,
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pp.746‐755, 2019.
https://doi.org/10.1109/TBCAS.2019.2918323
Dairoku Muramatsu website
https://mdairoku.com

The University of Electro-Communications 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585© 2023 The University of Electro-Communications.

Vol.2, January 2023

Video Profile：Innovation

Soft robotic devices : artificial muscles and soft materials for robotic applications
Jun Shintake, Assistant Professor, Department of Mechanical and Intelligent Systems EngineeringJun Shintake is developing soft actuators, sensors, and other robotic elements. As a base technology
he is using an artificial muscle called dielectric elastomer actuators that consist of a soft membranewith compliant electrodes on both sides. Applying voltages to the electrodes generates an expansionof the membrane as actuation. The principle of this artificial muscle forms the basis for creating
robots and other devices.
“We make all the devices by laminating thin film materials which are cut with a laser machine,”
explains Shintake. “This process allows the realization of various robotics elements such as actuators,sensors, pumps, and wearables.”In addition

to the development of soft robotic devices,Shintake is also working on environmentallyfriendly robots with the vision that in the future many different kinds of robots will blend into humansociety and the natural environment.
Within this context, if a robot malfunctions or is involved in an accident, then it becomes waste,leading to environmental destruction. This means there is a conflict in the desire to develop soft
robots that could cause environmental devastation. With this background, Shintake and his groupare developing soft robots using biodegradable materials that return to the soil.
The video includes examples ofa biodegradable soft actuator that exhibits bending actuation when

air is injected. Gelatin is used as the main material in this device. As illustrated in the video, theactuator gradually degrades and eventually blends into the soil.
However, air‐based actuators have limitations including the requirement for external pumps which
are often difficult to implement into a robot.
“I have developed biodegradable soft actuators that are electrically driven,” says Shintake. “Similar
to other examples from our research, we use gelatin together with oil and other biodegradable
materials. By using these materials, I have demonstrated that these actuators can generate muscle‐
like contraction movements.”
Shintake add that ultimately plants are promising biodegradable materials for robots. This video
includes a concept of a plant robot. Some kinds of plants exhibit physical deformations in response
to external stimuli. Shintake is exploiting this behavior for the development of plant‐based robots.

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Vol.2, January 2023

“I am also interested in biomimetic robots,” says Shintake. “In this case, I am developing a fish robotthat can fly into the air from underwater like a flying fish. My work covers a broad range of areas ofexpertise involving the development of soft robotic elements, biodegradable devices, and biomimeticrobots. Please contact me if you would like to know more about our research and collaborate in thedevelopment of these unique robotic elements.”
Further information
Jun Shintake
Assistant Professor, Department of Mechanical and Intelligent Systems Engineering, The University
of Electro‐Communications, Tokyo.
Website: http://kjk.office.uec.ac.jp/Profiles/74/0007381/prof_e.html
Research Highlight: Soft robotic gripper based on dielectric elastomer actuators

The University of Electro-Communications 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585© 2023 The University of Electro-Communications.