Metamaterial AMC backed Antenna for Body-worn Application at 2.45 GHz

Antennas worn on the human body for off-body\u3cbr/\u3ecommunication suffer from impedance detuning, a significant\u3cbr/\u3edrop in gain and efficiency due to the body degrading the antenna\u3cbr/\u3eperformance. An Artificial Magnetic Conductor (AMC), which is\u3cbr/\u3ea type of metamaterial could shield the antenna from radiating\u3cbr/\u3etowards the body, reducing the drop in gain and efficiency\u3cbr/\u3ewhile having sufficient impedance bandwidth and good coverage.\u3cbr/\u3eAn AMC backed Coplanar fed Inverted-F Antenna (CPW-IFA)\u3cbr/\u3eoperating at the 2.45 GHz Industrial, Scientific and Medical\u3cbr/\u3e(ISM) band was designed, simulated, fabricated and analyzed.\u3cbr/\u3eThe AMC was realized through a High Impedance Surface (HIS).\u3cbr/\u3eA unit cell is designed and a 2×2 array was used to back the CPWIFA\u3cbr/\u3eand then optimized. Results show that the novel antenna\u3cbr/\u3eis very robust to impedance detuning: the resonant frequency\u3cbr/\u3eshifting more than 50 times less than the reference CPW-IFA\u3cbr/\u3ewhen placed on the body. The simulated gain of 6.5 dBi and a 3\u3cbr/\u3edB beamwidth of 86° show good coverage away from the body.\u3cbr/\u3eThe gain of the antenna, when placed on the body, dropped only\u3cbr/\u3eby 0.8 dB while the radiation efficiency was 71% on the body. The\u3cbr/\u3ecompact 60 mm×60 mm×3.28 mm metamaterial backed antenna\u3cbr/\u3ewith a corresponding wavelength form factor of 0.5×0.5×0.027 is\u3cbr/\u3esuitable for integration with wearable electronics

Low-power communication for an implanted intracortical visual prosthesis

Assisting visually impaired people to see again using technology is quite challenging, especially for cases where most of the visual pathway is damaged. The only viable option is to stimulate the visual cortex directly. Sending the stimulation data to electrodes on the visual cortex is preferably done wirelessly to avoid infections and to ease mobility. The receiver on the implant poses a challenge in design, as the power supply is limited. In this paper, vital system requirements for this communication link are discussed. A low power system-level approach is presented which seeks to avoid power hungry components. This leads to the consideration of a bandpass sampled phase shift keying scheme via an inductive link. We propose a non-coherent digital demodulator, which relaxes the need for low phase noise oscillators which consume more power and, also avoids the use of phase locks loops. The overall communication system has a potential to deliver stimulation data to the implant side in the presence of simultaneous power transfer and reception of recorded data from the brain. Index Terms—Low-power, Inductive link, Non-coherent digital demodulator, Phase shift keying, Intracortical Visual Prosthesi

System design of a low-power wireless link for neural recording in a visual prosthesis

Restoring visual function in blind people through technology can be challenging but very beneficial in improving the quality of life. For most cases of blindness, the only option is to stimulate the visual cortex directly. Such a system requires external cameras, image processing and implanted electrodes. Powering, stimulating the brain, and recording neural activity is preferably done wirelessly to avoid infections. The wireless link for sending the neural activity (uplink) out of the brain is vital as the neural recording is for calibration and monitoring. Uplink requirements on (low-power) consumption at the implanted transmitter and a high data rate lead us to compare two promising wireless link options. A system-level analysis is carried out on the feasibility of impulse radio ultrawideband (IR-UWB) by a worst-case link budget. A low power CMOS IR-UWB transmitter consisting of an on-off keying (OOK) modulator and an impulse generator is proposed closely, fulfilling low-power and high data rate requirements

Low-power BPSK inductive data link for an implanted intracortical visual prosthesis

In making visually impaired people see again, for most cases the only option is to stimulate the visual cortex. In building such a system, it is desired that the communication to/from the implant and powering be done wirelessly to avoid infections. For the downlink, which is sending stimulation data to the implanted electrode, bandpass-sampled binary phase shift keying (BPSK) is chosen due to its potential for low-power consumption at its digital receiver. However, since an inductive link is most suited, designing practical inductive links with a flat band region to avoid poor phase transition and also refining the reset timing for imperfect transition times as well as designing low-power custom 1- bit Analog-to-digital converter is crucial. The bandpass-sampled BPSK system is designed and simulated at circuit level in Cadence using 180 nm CMOS technology at data rates of 0.5-4 Mbps and carrier frequency of 5-12 MHz. The improved bandpass-sampled BPSK system meets the requirements on data-rate, low-power consumption and robustness and is an integral part of the overall wireless communication and powering of the implanted intracortical visual prosthesis

System design of a low-power wireless link for neural recording in a visual prosthesis

Restoring visual function in blind people through technology can be challenging but very beneficial in improving the quality of life. For most cases of blindness, the only option is to stimulate the visual cortex directly. Such a system requires external cameras, image processing and implanted electrodes. Powering, stimulating the brain, and recording neural activity is preferably done wirelessly to avoid infections. The wireless link for sending the neural activity (uplink) out of the brain is vital as the neural recording is for calibration and monitoring. Uplink requirements on (low-power) consumption at the implanted transmitter and a high data rate lead us to compare two promising wireless link options. A system-level analysis is carried out on the feasibility of impulse radio ultrawideband (IR-UWB) by a worst-case link budget. A low power CMOS IR-UWB transmitter consisting of an on-off keying (OOK) modulator and an impulse generator is proposed closely, fulfiling low-power and high data rate requirements

Low-power communication for an implanted intracortical visual prosthesis

Assisting visually impaired people to see again using technology is quite challenging, especially for cases where most of the visual pathway is damaged. The only viable option is to stimulate the visual cortex directly. Sending the stimulation data to electrodes on the visual cortex is preferably done wirelessly to avoid infections and to ease mobility. The receiver on the implant poses a challenge in design, as the power supply is limited. In this paper, vital system requirements for this communication link are discussed. A low power system-level approach is presented which seeks to avoid power hungry components. This leads to the consideration of a bandpass sampled phase shift keying scheme via an inductive link. We propose a non-coherent digital demodulator, which relaxes the need for low phase noise oscillators which consume more power and, also avoids the use of phase locks loops. The overall communication system has a potential to deliver stimulation data to the implant side in the presence of simultaneous power transfer and reception of recorded data from the brain. Index Terms—Low-power, Inductive link, Non-coherent digital demodulator, Phase shift keying, Intracortical Visual Prosthesi

Low-power BPSK inductive data link for an implanted intracortical visual prosthesis

In making visually impaired people see again, for most cases the only option is to stimulate the visual cortex. In building such a system, it is desired that the communication to/from the implant and powering be done wirelessly to avoid infections. For the downlink, which is sending stimulation data to the implanted electrode, bandpass-sampled binary phase shift keying (BPSK) is chosen due to its potential for low-power consumption at its digital receiver. However, since an inductive link is most suited, designing practical inductive links with a flat band region to avoid poor phase transition and also refining the reset timing for imperfect transition times as well as designing low-power custom 1- bit Analog-to-digital converter is crucial. The bandpass-sampled BPSK system is designed and simulated at circuit level in Cadence using 180 nm CMOS technology at data rates of 0.5-4 Mbps and carrier frequency of 5-12 MHz. The improved bandpass-sampled BPSK system meets the requirements on data-rate, low-power consumption and robustness and is an integral part of the overall wireless communication and powering of the implanted intracortical visual prosthesis

Sub-Milliwatt Transceiver IC for Transcutaneous Communication of an Intracortical Visual Prosthesis

An intracortical visual prosthesis plays a vital role in partially restoring the faculty of sight in visually impaired people. Reliable high date rate wireless links are needed for transcutaneous communication. Such wireless communication should receive stimulation data (downlink) and send out neural recorded data (uplink). Hence, there is a need for an implanted transceiver that is low-power and delivers sufficient data rate for both uplink and downlink. In this paper, we propose an integrated circuit (IC) solution based on impulse radio ultrawideband using on-off keying modulation (OOK IR-UWB) for the uplink transmitter, and binary phase-shift keying (BPSK) with sampling and digital detection for the downlink receiver. To make the solution low-power, predominantly digital components are used in the presented transceiver test-chip. Current-controlled oscillators and an impulse generator provide tunability and complete the on-chip integration. The transceiver test-IC is fabricated in 180 nm CMOS technology and occupies only 0.0272 mm2. At 1.3 V power supply, only 0.2 mW is consumed for the BPSK receiver and 0.3 mW for the IR-UWB transmitter in the transceiver IC, while delivering 1 Mbps and 50 Mbps, respectively. Our link budget analysis shows that this test chip is suitable for intracortical integration considering the future off-chip antennas/coils transcutaneous 3–7 mm communication with the outer side. Hence, our work will enable realistic wireless links for the intracortical visual prosthesis