Challenges for Microelectronics in Non-Invasive Medical Diagnostics

Abstract

<jats:p>Microelectronics is emerging, sometimes with changing fortunes, as a key enabling technology in diagnostics. This paper reviews some recent results and technical challenges which still need to be addressed in terms of the design of CMOS analog application specific integrated circuits (ASICs) and their integration in the surrounding systems, in order to consolidate this technological paradigm. Open issues are discussed from two, apparently distant but complementary, points of view: micro-analytical devices, combining microfluidics with affinity bio-sensing, and gamma cameras for simultaneous multi-modal imaging, namely scintigraphy and magnetic resonance imaging (MRI). The role of integrated circuits is central in both application domains. In portable analytical platforms, ASICs offer miniaturization and tackle the noise/power dissipation trade-off. The integration of CMOS chips with microfluidics poses multiple open technological issues. In multi-modal imaging, now that the compatibility of the acquisition chains (thousands of Silicon Photo-Multipliers channels) of gamma detectors with Tesla-level magnetic fields has been demonstrated, other development directions, enabled by microelectronics, can be envisioned in particular for single-photon emission tomography (SPECT): a faster and simplified operation, for instance, to allow transportable applications (bed-side) and hardware pre-processing that reduces the number of output signals and the image reconstruction time.</jats:p>

Multiple Use SiPM Integrated Circuit (MUSIC) for Large Area and High Performance Sensors

“…SiPMs also have the benefit of large flexibility in the creation of 2D arrays of sensors, robustness, compactness, better suited for mass production and insensitivity to magnetic fields. However, SiPM capacitance can be at the level of 15 nF per square inch, which imposes serious requirements for a low noise and high speed readout [19]. A common approach to deal with this problem is to add the signal of several SiPMs [36].…”

“…A common approach to deal with this problem is to add the signal of several SiPMs [36]. Even in this scenario, requirements are stringent for an ASIC implementation if low noise, high bandwidth and large dynamic range have to be achieved [19].…”

“…These telescopes focus the flashes of Cherenkov light with nanosecond duration onto fast photo-sensor arrays where the signal is readout [16]. Medical imaging, including technologies such as positron emission tomography (PET) [17,18] and gamma single photon emission computed tomography (SPECT), also demand efficient photo-detectors [19,20].…”

“…In the last decade, a new type of photo-detector, the Silicon Photomultiplier (SiPM), was developed on the basis of the semiconductor technology as an alternative to PMTs [2,24]. Application specific integrated circuits (ASICs) for radiation sensors, in particular Front End (FE) electronics for SiPMs that are stable and perform at high count rates, are also needed to achieve the best performance from photo-sensor devices [19]. Typically, the FE electronics have to deal with the high terminal capacitance of the SiPMs when large photo-detection areas are required and therefore dedicated ASICs are needed [25].…”

“…Noise must be minimized while at the same time preserving the signal amplitude in order to optimize the SNR [19]. Note that, even if nominal gain of the SiPM is in the order of 10 [44,47].…”