No abstract

Optogenetics provide a potential alternative approach to the treatment of chronic pain, in which complex pathology often hampers efficacy of standard pharmacological approaches. Technological advancements in the development of thin, wireless, and mechanically flexible optoelectronic implants offer new routes to control the activity of subsets of neurons and nerve fibers in vivo. This study reports a novel and advanced design of battery-free, flexible, and lightweight devices equipped with one or two miniaturized LEDs, which can be individually controlled in real time. Two proof-of-concept experiments in mice demonstrate the feasibility of these devices. First, we show that blue-light devices implanted on top of the lumbar spinal cord can excite channelrhodopsin expressing nociceptors to induce place aversion. Second, we show that nocifensive withdrawal responses can be suppressed by green-light optogenetic (Archaerhodopsin-mediated) inhibition of action potential propagation along the sciatic nerve. One salient feature of these devices is that they can be operated via modern tablets and smartphones without bulky and complex lab instrumentation. In addition to the optical stimulation, the design enables the simultaneously wireless recording of the temperature in proximity of the stimulation area. As such, these devices are primed for translation to human patients with implications in the treatment of neurological and psychiatric conditions far beyond chronic pain syndromes.

The limited physical bandwidth of optical data links can be utilised better using pulse amplitude modulation (PAM) schemes. PAM can also be used to implement multiple channels on a single fibre to reduce the fibre count. In this paper, PAM is used with an additional amplitude level transmitting the clock associated with the data. This allows a direct detection of the clock from the signal. Frequent returns to this additional peak level are used to determine the signal strength at the receiver. The paper presents a very compact PCB implemented transmitter achieving a data rate of up to 400 Mbps. Furthermore, three PCB implemented receiver designs that cover different speed (20-400 Mbps) and cost/complexity ranges are presented including measurement results. The proposed solutions are compared to various industry standard solutions in terms of their achievable sampling rate and measurement delay resulting from connected sensors. It is concluded that PAM based data links represent an attractive alternative to the usual time domain multiplexing based 8b/10b encoded no-return-to-zero (NRZ) data links. They lead to an increase of the possible sampling rate (278 %) of the sensor and a decrease of the measurement delay (20 %), while keeping the same signal bandwidth and number of fibres.

The growing need for higher efficiency in converter systems and in power electronic systems in general has led to the implementation of more complex and sophisticated control algorithms. Often, the controller unit is separated from the sensors and the data has to be transmitted via an isolated channel. Plastic optical fibers are utilized for this task due to their low cost, high robustness and easy handling. In order to reduce the number of fibers, intensity modulation can be used to transmit multiple signals over a single optical fiber. A recently introduced modulation scheme with an additional intensity level indicating the clock allows a simple clock recovery at the receiver. In this paper, three receiver concepts based on this modulation scheme are presented for medium data rates in the range of 20 -50 Mbps which is sufficient for most power electronic applications. The low complexity and small footprint of the proposed concepts facilitate the system integration. Furthermore, a more compact system can be designed due to the lower number of necessary fibers and corresponding transmitter and receiver circuits.