Showing papers by "Helena Gleskova published in 2019"
TL;DR: In this article, lowvoltage p-channel organic thin-film transistors based on [n]phenacene (n = 5, 6 or 7) were fabricated on glass and on flexible poly(ethylene 2,6-naphthalate) (PEN) substrates.
12 citations
10 Jul 2019
TL;DR: The results show that only a subset of the 6 sensors is needed for predicting these 9 sitting postures with high accuracy, which opens up the possibility for intelligent, real-time monitoring systems that can improve safety and wellbeing of today’s office workers.
Abstract: Six flexible force sensors, two on the backrest and four on the seat, were embedded in the upholstery of an off-the-shelf office chair to enable non-intrusive monitoring of sitting postures. Besides the sensors, the monitoring platform comprises an Arduino Nano microcontroller with Wi-Fi transmitter, embedded on the chair, a Wi-Fi receiver communicating with a remote server and a Graphical User Interface (GUI) showing real-time readings. Approximately 26,000 observations corresponding to 9 different postures were collected, labelled and classified using supervised machine learning. The results show that only a subset of the 6 sensors is needed for predicting these 9 sitting postures with high accuracy. This opens up the possibility for intelligent, real-time monitoring systems that can improve safety and wellbeing of today’s office workers.
10 citations
10 Jul 2019
TL;DR: In this paper, the results of compact modeling, implemented in Matlab Simulink, applied to organic thin-film transistors (OTFTs) with multi-finger contacts based on dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (DNTT) are presented.
Abstract: Organic thin-film transistors (OTFTs) with multi-finger contacts based on dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (DNTT) exhibit near-zero turn-on voltage, hysteresisfree behavior, and high transconductance of 30-80 µA at V DS = V GS = −2 V. [1] In addition, common-source amplifiers based on such transistors deliver voltage gain even when the supply voltage is limited to 5 V, making them attractive for flexible/ wearable analog sensors. This paper presents the results of compact modeling, implemented in Matlab Simulink, applied to such transistors. The measured transistor transfer characteristics are used to extract the parameters for the semiempirical model. The model was validated in 3 ways on 8 OTFTs with varied geometries and substrates (glass or PEN). The validation included calculations of (a) transistor output characteristics, (b) a.c. drain currents for 1 Hz sinusoidal gate voltages, and (c) output voltages of the common-source amplifier, and their comparison to the measured data.
1 citations
10 Jul 2019
TL;DR: In this paper, the geometry of DNTT transistors with interdigitated source/drain contacts was studied and the channel width-to-length ratio W/L was achieved by varying the W from 12 to 18 mm and L from 20 to 50 mm, leading to W /L of ~300 to ~900.
Abstract: Low threshold voltage, high transconductance DNTT transistors (OTFTs) with interdigitated source/drain contacts can provide low-voltage transistor amplifiers with a.c. cut-off frequency in excess of 10 kHz [1] , making them suitable for wearable sensors. This paper presents an in-depth study of the geometry of such transistors fabricated on PEN. Changes in channel width-to-length ratio W / L were achieved by varying the W from ~12 to ~18 mm and L from 20 to 50 μm, leading to W / L of ~300 to ~900. The OTFTs exhibit threshold voltage from −0.33 to −0.74 V, field-effect mobility from 0.17 to 0.42 cm 2 /V⋅s, on-current from 28 to 67 μA (at V GS = V DS = −2 V), off-current from 6×10 -12 to 7×10 -8 A, and subthreshold slope from 65 to 266 mV/decade. While the OTFTs exhibit large on-state drain current and a.c. transconductance, smaller L leads to a slightly reduced mobility. In addition, the OTFTs with the largest W of 18.23 mm possess the lowest off-state drain current and subthreshold slope.