Two versions of a PPG/ECG combined system have been realized and tested. In a first version a multisite system has been equipped by integrating 3 PPG optodes and 3 ECG leads, whereas in another setup a portable version has been carried out. Both versions have been realized by equipping the optical probes with SiPM detectors. SiPM technology is expected to bring relevant advantages in PPG systems and overcome the limitations of physiological information extracted by state of the art PPG, such as poor sensitivity of detectors used for backscattered light detection and motion artifacts seriously affecting the measurements repeatability and pulse waveform stability. This contribution presents the intermediate results of development in the frame of the European H2020-ECSEL Project ASTONISH (n.692470), including SiPM based PPG optodes, and the acquisition electronic components used for simultaneous recording of both PPG/ECG signals. The accurate monitoring of dynamic changes of physiological data through a non-invasive integrated system, including hemodynamic parameters (e.g. heart rate, tissue perfusion etc.) and heart electrical activity can play an important role in a wide variety of applications (e.g. healthcare, fitness and cardiovascular disease). In this work we describe also a method to process PPG waveform according to a PPG process pipeline for pattern recognition. Some examples of PPG waveform signal analysis and the preliminary results of acquisitions obtained through the intermediate demonstrator systems have been reported.

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In this paper, we report on the performances of silicon photomultipliers (SiPMs) with commercial long-pass interferential and plastic filters integrated on the detector's package for environmental light rejection. Several applications, including functional near infrared (NIR) spectroscopy or light detection and ranging, would benefit from the use of highly sensitive detectors like SiPMs with optimized electro-optical characteristics in NIR wavelength range. To this purpose, it is fundamental to reduce the absorption of environmental spurious light leading in application to a decrease of the detector's sensitivity, especially for very weak photon fluxes. We will show how the use of both types of filters has a relevant impact on the electro-optical performances of the bare detectors, in terms of cross talk reduction at high overvoltage values, detection efficiency, spectral response and capability to shield effectively the devices from the absorption of stray light, at the different light wavelengths used for the measurements.

Drastic efforts have been realized these last years in order to develop complementary organic technology. This is the essential key to produce elementary lowcost circuits for digital and analog applications. Different techniques [1][2][3] are available nowadays to obtain both N-and/or P-type organic devices. Screen printing is one of the most highly awaited low-cost techniques that can be used to produce organic devices and circuits. It has been widely used in P-type organic technologies [4,5]. Now that N-type semiconductors have become much more easily processed, developers are seeking a complete CMOS and lifetime robust technology. Many previous works have reported on a complete solution based on CMOS technology [6][7][8]. Large-area-compatible organic processes have also been demonstrated [9]. Nevertheless some of the technological steps in these latter reports are not fully printed and/or still present some lithography/vacuum deposition steps. We present here a complete fully printed CMOS technology on flexible substrates showing acceptable device performances and digital/analog circuit functionalities, which can lead to more complex designs.Based on our design toolkit we have processed a testchip including single devices, inverters, ring oscillators and simple analog circuits such as current mirrors, differential pairs and cascodes (see Fig. 18.4.7) in order to show the feasibility of our organic CMOS technology.Our organic CMOS top-gate design fabrication is carried out on a 10×10 cm 2 gold-plated 125μm-thick Polyethylene-naphtalate (PEN) substrate. The first step consists of a patterning by laser ablation of source/drain electrodes, which also serves as first level of interconnections, where we attain a 5μm line/space resolution. P-type and N-type semiconductors are then screen printed on the foil and then annealed at a temperature of 100°C in normal atmospheric conditions. The gate dielectric polymer is screen printed above both semiconductors leaving open vias for level interconnections and then annealed. Finally the gate and the second interconnection level are printed with same technique using a conductive silver ink. A final annealing step at 100°C is performed.We have carried out all our measurements in ambient temperature and pressure. In Fig 18.4.1 we show the transfer and output characteristics of both types of devices for the geometry W/L = 2000/20μm. We observe that both types of devices show equivalent levels of ON and OFF state currents. Table 1 (see Fig. 18.4.2) summarizes the important electrical parameters for 2 different transistor geometries. Threshold voltage and saturation mobility for both types of devices have been monitored on the whole set of available transistors to evaluate their respective dispersions. Figure 18.4.3 shows the distributions of N-and P-type threshold voltage and mobility.For digital applications, elementary inverters and ring oscillators have been tested. In Fig. 18.4.4, we present a fully functional inverter (W n =W p =1000μm and L=20μm) and its corresponding 7-st...

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The development and validation of a system for multi-site photoplethysmography (PPG) and electrocardiography (ECG) is presented. The system could acquire signals from 8 PPG probes and 10 ECG leads. Each PPG probe was constituted of a light-emitting diode (LED) source at a wavelength of 940 nm and a silicon photomultiplier (SiPM) detector, located in a back-reflection recording configuration. In order to ensure proper optode-to-skin coupling, the probe was equipped with insufflating cuffs. The high number of PPG probes allowed us to simultaneously acquire signals from multiple body locations. The ECG provided a reference for single-pulse PPG evaluation and averaging, allowing the extraction of indices of cardiovascular status with a high signal-to-noise ratio. Firstly, the system was characterized on optical phantoms. Furthermore, in vivo validation was performed by estimating the brachial-ankle pulse wave velocity (baPWV), a metric associated with cardiovascular status. The validation was performed on healthy volunteers to assess the baPWV intra- and extra-operator repeatability and its association with age. Finally, the baPWV, evaluated via the developed instrumentation, was compared to that estimated with a commercial system used in clinical practice (Enverdis Vascular Explorer). The validation demonstrated the system’s reliability and its effectiveness in assessing the cardiovascular status in arterial ageing.

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