TY  - JOUR
AB  - Attention to Black Carbon (BC) has been rising due to its effects on human health as well its contribution to climate change. Measurements of BC are challenging, as currently used devices are either expensive or impractical for continuous monitoring. Here, we propose an optoacoustic sensor to address this problem. The sensor utilizes a novel ellipsoidal design for refocusing the optoacoustic signal with minimal acoustic energy losses. To reduce the cost of the system, without sacrificing accuracy, an overdriven laser diode and a Quartz Tuning Fork are used as the light source and the sound detector, respectively. The prototype was able to detect BC particles and to accurately monitor changes in concentration in real time and with very good agreement with a reference instrument. The response of the sensor was linearly dependent on the BC particles concentration with a normalized noise equivalent absorption coefficient (NNEA) for soot equal to 7.39 × 10−9 W cm−1 Hz−1/2. Finally, the prototype was able to perform NO2 measurements, demonstrating its ability to accurately monitor both particulate and gaseous pollutants. The proposed sensor has the potential to offer a significant economic impact for BC environmental measurements and source appointment technologies.
AU  - Stylogiannis, A.
AU  - Kousias, N.*
AU  - Kontses, A.*
AU  - Ntziachristos, L.*
AU  - Ntziachristos, V.
C1  - 61394
C2  - 50206
CY  - St Alban-anlage 66, Ch-4052 Basel, Switzerland
TI  - A low-cost optoacoustic sensor for environmental monitoring.
JO  - Sensors
VL  - 21
IS  - 4
PB  - Mdpi
PY  - 2021
SN  - 1424-8220
ER  - 

TY  - JOUR
AB  - Photoacoustic (PA) imaging is a hybrid imaging technique that can provide both structural and functional information of biological tissues. Due to limited permissible laser energy deposited on tissues, highly sensitive PA imaging is required. Here, we developed a 20 MHz lead zirconium titanate (PZT) transducer (1.5 mm x 3 mm) with front-end amplifier circuits for local signal processing to achieve sensitivity enhanced PA imaging. The electrical and acoustic performance was characterized. Experiments on phantoms and chicken breast tissue were conducted to validate the imaging performance. The fabricated prototype shows a bandwidth of 63% and achieves a noise equivalent pressure (NEP) of 0.24 mPa/root Hz and a receiving sensitivity of 62.1 mu V/Pa at 20 MHz without degradation of the bandwidth. PA imaging of wire phantoms demonstrates that the prototype is capable of improving the detection sensitivity by 10 dB compared with the traditional transducer without integrated amplifier. In addition, in vitro experiments on chicken breast tissue show that structures could be imaged with enhanced contrast using the prototype and the imaging depth range was improved by 1 mm. These results demonstrate that the transducer with an integrated front-end amplifier enables highly sensitive PA imaging with improved penetration depth. The proposed method holds the potential for visualization of deep tissue structures and enhanced detection of weak physiological changes.
AU  - Yang, C.*
AU  - Jian, X.*
AU  - Zhu, X.*
AU  - Lv, J.*
AU  - Jiao, Y.*
AU  - Han, Z.*
AU  - Stylogiannis, A.
AU  - Ntziachristos, V.
AU  - Sergiadis, G.
AU  - Cui, Y.*
C1  - 58799
C2  - 48334
CY  - St Alban-anlage 66, Ch-4052 Basel, Switzerland
TI  - Sensitivity enhanced photoacoustic imaging using a high-frequency PZT transducer with an integrated front-end amplifier.
JO  - Sensors
VL  - 20
IS  - 3
PB  - Mdpi
PY  - 2020
SN  - 1424-8220
ER  - 

TY  - JOUR
AB  - This paper comprehensively reviews the emerging topic of optoacoustic imaging from the image reconstruction and quantification perspective. Optoacoustic imaging combines highly attractive features, including rich contrast and high versatility in sensing diverse biological targets, excellent spatial resolution not compromised by light scattering, and relatively low cost of implementation. Yet, living objects present a complex target for optoacoustic imaging due to the presence of a highly heterogeneous tissue background in the form of strong spatial variations of scattering and absorption. Extracting quantified information on the actual distribution of tissue chromophores and other biomarkers constitutes therefore a challenging problem. Image quantification is further compromised by some frequently-used approximated inversion formulae. In this review, the currently available optoacoustic image reconstruction and quantification approaches are assessed, including back-projection and model-based inversion algorithms, sparse signal representation, wavelet-based approaches, methods for reduction of acoustic artifacts as well as multi-spectral methods for visualization of tissue bio-markers. Applicability of the different methodologies is further analyzed in the context of real-life performance in small animal and clinical in-vivo imaging scenarios.
AU  - Lutzweiler, C.
AU  - Razansky, D.
C1  - 24788
C2  - 31679
SP  - 7345-7384
TI  - Optoacoustic imaging and tomography: Reconstruction approaches and outstanding challenges in image performance and quantification.
JO  - Sensors
VL  - 13
IS  - 6
PB  - MDPI
PY  - 2013
SN  - 1424-8220
ER  - 

TY  - JOUR
AB  - Autoinducer signals enable coordinated behaviour of bacterial populations, a phenomenon originally described as quorum sensing. Autoinducer systems are often controlled by environmental substances as nutrients or secondary metabolites (signals from neighbouring organisms. In cell aggregates and biofilms gradients of signals and environmental substances emerge. Mathematical modelling is used to analyse the functioning of the system. We find that the autoinducer regulation network generates spatially heterogeneous behaviour, up to a kind of multicellularity-like division of work, especially under nutrient-controlled conditions. A hybrid push/pull concept is proposed to explain the ecological function. The analysis allows to explain hitherto seemingly contradicting experimental findings.
AU  - Hense, B.A.
AU  - Müller, J.*
AU  - Kuttler, C.*
AU  - Hartmann, A.
C1  - 7288
C2  - 29648
SP  - 4156-4171
TI  - Spatial heterogeneity of autoinducer regulation systems.
JO  - Sensors
VL  - 12
IS  - 4
PB  - MDPI
PY  - 2012
SN  - 1424-8220
ER  - 

TY  - JOUR
AB  - We have fabricated organic field-effect transistors (OFETs) with regioregular poly(3-hexylthiophene) (P3HT) operable at low-voltages in liquid solutions, suitable for in vitro biosensing applications. Measurements in electrolytes have shown that the performance of the transistors did not deteriorate and they can be directly used as ion-sensitive transducers. Furthermore, more complex media have been tested, with the perspective of cell analysis. Degradation effects acting on the device operating in liquid could be partly compensated by adopting an alternate current measuring mode.
AU  - Scarpa, G.*
AU  - Idzko, A.L.
AU  - Yadav, A.*
AU  - Thalhammer, S.
C1  - 812
C2  - 27703
SP  - 2262-2273
TI  - Organic ISFET based on poly(3-hexylthiophene).
JO  - Sensors
VL  - 10
IS  - 3
PB  - Molecular Diversity preservation International-MDPI
PY  - 2010
SN  - 1424-8220
ER  -