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Size and absolute concentration of suspensions of nanoparticles are important information for the study and development of new materials and products in different industrial applications spanning from biotechnology and pharmaceutics to food preparation and conservation. Laser Transmission Spectroscopy (LTS) is the only methodology able to measure nanoparticle size and concentration by performing a single measurement. In this paper we report on a new variable gain calibration procedure for LTS-based instruments allowing to decrease of an order of magnitude the experimental indetermination of the particle size respect to the conventional LTS based on the double ratio technique. The variable gain calibration procedure makes use of a specifically designed tunable-gain, dual-channel, dual-phase Lock-In Amplifier (LIA) whose input voltage signals are those ones generated by two Si photodiodes that measure the laser beam intensities passing through the sample containing the nanoparticles and a reference optical path. The LTS variable gain calibration procedure has been validated by firstly using a suspension of NIST standard polystyrene nanoparticles even 36 hours after the calibration procedure was accomplished. The paper reports in detail the LIA implementation describing the design methodologies and the electronic circuits. As a case example of the characterization of biological nanostructures, we demonstrate that a single LTS measurement allowed to determine size density distribution of a population of extracellular vesicles extracted from orange juice (25 nm in size) with the presence of their aggregates having a size of 340 nm and a concentration smaller than 3 orders of magnitude.

In this paper we report on the fabrication, implementation and experimental characterization of an integrated bidirectional communication System-on-Chip (SoC) for transcutaneous bidirectional optical biotelemetry links. The proposed architecture implements a UWB-inspired pulsed coding technique and contains a transmitter and a receiver to achieve a simultaneous bidirectional link. The transmitter generates sub-nanosecond current pulses to directly drive off-chip pulsed vertical cavity semiconductor lasers by means of a digital data coding subsystem and all the needed bias and driving circuits. On the other hand, the receiver manages off-chip fast Si photodiodes and includes signal conditioning, detection and digital data decoding circuits to support high bit rate and energy efficient communication links. The entire solution designed at transistor level has been fabricated in AMS 0.35µm standard CMOS technology into a compact silicon footprint lower than 0.13mm2 employing only 113 transistors and 1 resistor. A specific PCB has been developed together with a suitable test bench implemented on Xilinx Virtex-6 XC6VLX240T FPGA board to properly evaluate the performances and the main characteristics of the ASIC. Furthermore, a 6 GHz, 20 GS/s LeCroy WaveMaster 8600A digital oscilloscope has been employed to investigate the system time response. Preliminary experimental results validated the correct functionality of the overall integrated system demonstrating also its capability to operate, also in a bidirectional mode, at bit rates up to 250 Mbps with pulse widths up to 1.2ns and a minimum total power efficiency of about 160 pJ/bit in the conditions for which the transmitter and the receiver work simultaneously onto the same chip. These results make the developed solution suitable for high performances bidirectional optical biotelemetry links to be applied, e.g., to implantable neural recording/stimulation transcutaneous platforms that generally require communication channels with high up- e down-link bit rates at extremely low energy levels.

This paper describes an integrated communication system, implementing a UWB-inspired pulsed coding technique, for an optical transcutaneous biotelemetry. The system consists of both a transmitter and a receiver facilitating a bidirectional link. The transmitter includes a digital data coding circuit and is capable of generating sub-nanosecond current pulses and directly driving an off-chip semiconductor laser diode including all bias and drive circuits. The receiver includes an integrated compact PN-junction photodiode together with signal conditioning, de- tection and digital data decoding circuits to enable a high bit rate, energy efficient communication. The proposed solution has been implemented in a commercially available 0.35 μ m CMOS technology provided by AMS. The circuit core occupies a compact silicon footprint of less than 0.13 mm 2 (only 113 transistors and 1 resistor). Post-layout simulations have validated the overall system operation demonstrating the ability to operate at bit rates up to 500 Mbps with pulse widths of 300 ps with a total power efficiency (transmitter + receiver) lower than 74 pJ/bit. This makes the system ideally suited for demanding applications that require high bit rates at extremely low energy levels. One such application is implantable brain machine interfaces requiring high uplink bitrates to transmit recorded data externally through a transcutaneous communication channel.

This paper presents an optical communication system, implementing a UWB-inspired pulsed coding technique, for emerging high throughput bio-applications such as brain machine interfaces. The proposed solution employs sub-nanosecond laser pulses that, compared to the state-of-the-art, allows for high bit rate transmissions and reduced power consumption. The overall architecture consist of a transmitter and receiver that employ a pulsed semiconductor laser and a small sensitive area photodiode. This can allow for CMOS integration into a compact silicon footprint (estimated lower than 1 mm2 in a 0.18 μm technology). The analogue circuits presented herein have been implemented using discrete off-the-shelf components. These provide the bias and drive signals for laser pulse generation, photodiode signal detection and conditioning. Moreover, the digital sub-system for data coding and decoding processes have been implemented on a FPGA board through VHDL description language. Experimental results validate the overall functionality of the proposed system using a diffuser between transmitter and receiver to emulate skin/tissue. This shows the capability of operating at bit rates up to 250 Mbps achieving BER less than 10−9 and power efficiency as low as 24pJ/bit. These results enable, for example, the transmission of a 1000-channel neural recording system sampled at 16kHz with 16-bit resolution.

This paper reports on a pulsed coding technique based on optical Ultra-wideband (UWB) modulation for wireless implantable biotelemetry systems allowing for high data rate link whilst enabling significant power reduction compared to the state-of-the-art. This optical data coding approach is suitable for emerging biomedical applications like transcutaneous neural wireless communication systems. The overall architecture implementing this optical modulation technique employs sub-nanosecond pulsed laser as the data transmitter and small sensitive area photodiode as the data receiver. Moreover, it includes coding and decoding digital systems, biasing and driving analogue circuits for laser pulse generation and photodiode signal conditioning. The complete system has been implemented on Field-Programmable Gate Array (FPGA) and prototype Printed Circuit Board (PCB) with discrete off-the-shelf components. By inserting a diffuser between the transmitter and the receiver to emulate skin/tissue, the system is capable to achieve a 128 Mbps data rate with a bit error rate less than 10−9 and an estimated total power consumption of about 5 mW corresponding to a power efficiency of 35.9 pJ/bit. These results could allow, for example, the transmission of an 800-channel neural recording interface sampled at 16 kHz with 10-bit resolution.

We propose an optical UWB modulation based on a new pulsed coding technique for wireless implantable biotelemetry. The solution employs sub-nanosecond laser pulses allowing for both high data rates and reduction of the power consumption compared to the state-of-the-art. Thus, the proposed approach is suitable for upcoming biomedical systems like autonomous implantable neural devices. The developed architecture consists of a transmitter and a receiver employing a pulsed semiconductor laser and a small sensitive area photodiode, respectively, and includes coding and decoding digital systems, biasing and driving analogue circuits for laser pulse generation and photodiode signal conditioning. Experimental findings, obtained by employing discrete components prototype PCBs and FPGA implementations, validate the novel technique showing the capabilities to achieve a BER less than 10 -9 with data rates up to 250Mbps and an estimated power consumption lower than 5mW. These results enable, for example, the transmission of a 1000-channel neural recording system sampled at 16 kHz with 16-bit resolution.