Project: IEEE P802.15 Working Group for Wireless Body Area Networks (WBANs) Submission Title: [Limitations of WPT carrier frequency for the Implant Devices] Date Submitted: [Mar. 2009] Source: [KiBum Kwon, YangMoon Yoon, SangYun Lee, WonHo Jang] Company [KORPA (Korea Radio Promotion Agency)] Voice: [+82 2 2142 2166] E-Mail: [wrecker@korpa.or.kr] Re: [] Abstract: [This document presents considerations of WPT carrier frequency for the implant devices] Notice: This document has been prepared to assist the IEEE P802.15. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15.

Limitations of WPT carrier frequency for the Implant Devices KiBum Kwon, YangMoon Yoon, SangYun Lee, WonHo Jang KORPA (Korea Radio Promotion Agency) Good morning (or afternoon). Nice to meet you. I’m glad to see you again after Dallas meeting. Let me introduce myself. My name is KiBum Kwon. And I’m senior engineer working in KORPA. OK, now I’d like to explain why wireless power transmission scheme need for the implant devices and what limitations are considered for using wireless power transmission.

Purpose and Contents Contents This document presents considerations of WPT (Wireless Power Transmission) carrier frequency for the implant devices Contents Advantages of WPT What we consider about WPT for TG 6 Standardization? What kind of frequency we could consider for WPT? General Public Exposure limits to electromagnetic radiation Future Works for Proposals of TG 6 Standardization with Wireless Power Transmission This document presents considerations of WPT carrier frequency for the implant devices. 3

Energy Limitation of Implant Devices It is difficult to change and charge the implant device’s battery rather than that of out-body device. The life time of implant device for WBAN depends on the battery capacity. Since shape and size of battery is constraint. Well, when we design implant devices, we should be faced with energy limitation problem. Because it is difficult to change and charge battery of the implant devices rather than that of out-body devices. As you know a battery capacity depends on battery shape and size. Of course, battery capacity could be various according to what schemes are used at the same constraint. This figure shows the mini battery in capsule endoscope. E.g.) Capsule Endoscope 4

Advantages of Wireless Power Transmission We can extend the lifetime of implant device and be free to the power-constrained characteristics. We can reduce the battery size in manufacturing the implant device. So, minimizing the device size If we use wireless power transmission for implant devices, we can extend the life time of implant devices and can be free from the power-constrained characteristics. Some kind of device’s life time could become semi-permanent. And we can also reduce the battery size in manufacturing the implant device. Finally, we may not take battery into account. So, we can make the device without considering of space for battery. 5

What we consider about WPT for TG 6 Standardization? WPT Schemes RF radiation Inductive coupling …ETC We may not need to consider currently about what WPT schemes used. But, we should check about WPT carrier frequency since it is related to Safety and Efficiency of Power Transmission. OK, Let me see the items for TG6 standardization with WPT. WPT schemes could be various. RF radiation, Inductive coupling, etc… Now a day, we may not need to consider about what WPT schemes used. Because, we should say about requirements for WPT first. For example, the conditions for safety and efficiency of power transmission, etc. These are mainly related to WPT carrier frequency. So, we should check about WPT carrier frequency first. 6

What kind of frequency we could consider for WPT? 90kHz ~ 110kHz (a) Traditional frequency band for inductive coupling 400MHz (b) Nearby MICS band 2.4GHz (c) ISM band We assumed some carrier frequencies for WPT. First, from 90kHz to 110kHz band. This band has used for inductive coupling. And than 400MHz band. This band is selected why Nearby MICS band. Finally, 2.4GHz band. This band is one of the ISM band and high frequency that we could consider. 7

What kind of frequency we could consider for WPT? Selection of Frequency for Wireless Power Transmission Safety Probability of affecting to tissues in body could be increased in E-H field using high frequency Efficiency of Power Transmission High Power Transmission Rate could be achieved by carrier frequency and transmit power increasing OK, well, when we select the WPT carrier frequency, what factors should be considered? Safety and efficiency of power transmission issues are sensitive according to carrier frequency. Probability of affecting to tissues in body could be increasing in E-H filed using high frequency and transmit power. And High power Transmission rate could be achieved by carrier frequency and transmit power increasing. Safty and Efficiency are trade off. Safty  Trade off  Efficiency 8

General Public Exposure limits to electromagnetic radiation Exposure limits of E-field and H-field strength (a) (b) (c) (a) (b) (c) Let me check how frequency and transmit power are limited in several country. According to the grape, Both of E-field and H-field have no limits or high exposure limits around 100kHz. But the limit levels are going down according to increasing frequency. However, the limit levels higher than 400MHz after 2 or 3GHz. Both of E-field and H-field cases, which have no limits (U.S. China, Canada, Japan) or high exposure limits (Korea, U.K.) in (a) band (yellow). But, the limit levels are going down in (b) band (cyan). The limit levels are higher than (b) band after (c) band (pink). 9

General Public Exposure limits to electromagnetic radiation Exposure limits of Power density (a) (b) (c) The limits of power density level are not existed below 1MHz. After 1MHz, the exposure limits of power density grape show the similar to exposure limits of E-H field. The limits of power density level are not existed below 1MHz. The limits are severest over 10MHz to 400MHz. But, the limits are more increased after (c) band. 10

Proposals for Standardization Future Works for Proposals of TG 6 Standardization with Wireless Power Transmission Proposals for Standardization A set of WPT carrier frequencies according to applications of WBAN Maximum WPT Tx. Power depends on set of WPT carrier frequencies within Exposure limits of E-H field and Power density OK, we will propose about WPT for TG6 standardization at next meeting. First, A set of WPT carrier frequencies according to application of WBAN. And Maximum WPT Tx. Power depends on set of WPT carrier frequencies within exposure limits of E-H field and power density. and we also consider the another factors like SAR. 11

Thank you for your attention! Q & A.

Reference [1] WHO, International EMF project (http://www.who.int/docstore/peh-emf/EMFStandards/who-0102/Worldmap5.htm) 13