Peering into the dark (ages) with low-frequency space interferometers: Using the 21-cm signal of neutral hydrogen from the infant universe to probe fundamental (Astro)physics.

The Dark Ages and Cosmic Dawn are largely unexplored windows on the infant Universe (z ~ 200-10). Observations of the redshifted 21-cm line of neutral hydrogen can provide valuable new insight into fundamental physics and astrophysics during these eras that no other probe can provide, and drives the design of many future ground-based instruments such as the Square Kilometre Array (SKA) and the Hydrogen Epoch of Reionization Array (HERA). We review progress in the field of high-redshift 21-cm Cosmology, in particular focussing on what questions can be addressed by probing the Dark Ages at z > 30. We conclude that only a space- or lunar-based radio telescope, shielded from the Earth's radio-frequency interference (RFI) signals and its ionosphere, enable the 21-cm signal from the Dark Ages to be detected. We suggest a generic mission design concept, CoDEX, that will enable this in the coming decades.

Low-Power Wireless Data Transfer System for Stimulation in an Intracortical Visual Prosthesis.

There is a growing interest to improve the quality of life of blind people. An implanted intracortical prosthesis could be the last resort in many cases of visual impairment. Technology at this moment is at a stage that implementation is at sight. Making the data communication to and from the implanted electrodes wireless is beneficial to avoid infection and to ease mobility. Here, we focus on the stimulation side, or downlink, for which we propose a low-power non-coherent digital demodulator on the implanted receiver. The experimentally demonstrated downlink is on a scaled-down version at a 1 MHz carrier frequency showing a data rate of 125 kbps. This provides proof of principle for the system with a 12 MHz carrier frequency and a data rate of 4 Mbps, which consumes under 1 mW at the receiver side in integrated circuit (IC) simulation. Due to its digital architecture, the system is easily adjustable to an ISM frequency band with its power consumption scaling linearly with the carrier frequency. The tested system uses off-the-shelf coils, which gave sufficient bandwidth, while staying within safe SAR limits. The digital receiver achieved a reduction in power consumption by skipping clock cycles of redundant bits. The system shows a promising pathway to a low-power wireless-enabled visual prosthesis.

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.