Ants Koel

Ants Koel

orcid

Research Focus & Metrics

Academic Career Length

9Years (2018-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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29 January 2021 in IEEE Access
Verified
Journal Article
Open access
UPUdayan Patankar
Udayan Patankar
AKAnts Koel
Ants Koel
The electronics world is very well described in two distinct but dependent interdisciplinary areas, namely hardware and software. Arithmetic operations are very vital building blocks of an electronic system. An algorithm is a systematic arrangement that helps develop a sophisticated electronic system, including hardware and software aspects. Addition, subtraction, multiplication, and division are critical elements of arithmetic implementation in the electronic system, but fewer efforts have been made to implement division than other arithmetic operations, even though the number of transistors on a chip is increasing beyond the Moore's law prediction. It is quite complicated to implement arithmetical operations; here, a sophisticated algorithm is essential to successful implementation. Technological upgrades are leading to a new paradigm of applications, where the performance of a division circuit or block is a vital and critical feature of a successful system. The lexicon of algorithms used in the implementation of the division operation in electronics systems is discussed in detail in the present article, which indicates the mathematical formulation, criticality, conversion pattern, hardware requirements, and logic used for conversion. The current report describes the broad classification of dividers into basic classes named digit recurrence, high radix, functional iteration, estimation, a look-up table, and variable latency. It also illustrates that, in practical implementation, many algorithms have been developed that combine one or many classes and are implemented with different hardware architectures. The study indicated the possibility of improving the presently available algorithms or creating a new algorithm to enhance practical implementation.

3 January 2020 in Nanomaterials
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Journal Article
Open access
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MRMuhammad Rashid
Muhammad Rashid
AKAnts Koel
Ants Koel
TRToomas Rang
Toomas Rang
During the last few years graphene has emerged as a potential candidate for electronics and optoelectronics applications due to its several salient features. Graphene is a smart material that responds to any physical change in its surrounding environment. Graphene has a very low intrinsic electronic noise and it can detect even a single gas molecule in its proximity. This property of graphene makes is a suitable and promising candidate to detect a large variety of organic/inorganic chemicals and gases. Typical solid state gas sensors usually requires high operating temperature and they cannot detect very low concentrations of gases efficiently due to intrinsic noise caused by thermal motion of charge carriers at high temperatures. They also have low resolution and stability issues of their constituent materials (such as electrolytes, electrodes, and sensing material itself) in harsh environments. It accelerates the need of development of robust, highly sensitive and efficient gas sensor with low operating temperature. Graphene and its derivatives could be a prospective replacement of these solid-state sensors due to their better electronic attributes for moderate temperature applications. The presence of extremely low intrinsic noise in graphene makes it highly suitable to detect a very low concentration of organic/inorganic compounds (even a single molecule ca be detected with graphene). In this article, we simulated a novel graphene nanoribbon based field effect transistor (FET) and used it to detect propane and butane gases. These are flammable household/industrial gases that must be detected to avoid serious accidents. The effects of atmospheric oxygen and humidity have also been studied by mixing oxygen and water molecules with desired target gases (propane and butane). The change in source-to-drain current of FET in the proximity of the target gases has been used as a detection signal. Our simulated FET device showed a noticeable change in density of states and IV-characteristics in the presence of target gas molecules. Nanoscale simulations of FET based gas sensor have been done in Quantumwise Atomistix Toolkit (ATK). ATK is a commercially available nanoscale semiconductor device simulator that is used to model a large variety of nanoscale devices. Our proposed device can be converted into a physical device to get a low cost and small sized integrated gas sensor.

20 April 2019 in Sensors
Verified
Journal Article
Open access
PDF file
JOJaan Ojarand
Jaan Ojarand
MMMart Min
Mart Min
AKAnts Koel
Ants Koel
Impedance spectroscopy is a common approach in assessing passive electrical properties of biological matter. However, several problems appear in microfluidic devices in connection with the requirement for high sensitivity of signal acquisition from small volume sensors. The developed compact and inexpensive analyzer provides impedance spectroscopy measurement from three sensors, both connected in direct and differential modes. Measurement deficiencies are reduced with a novel design of sensors, measurement method, optimized electronics, signal processing, and mechanical design of the analyzer. Proposed solutions are targeted to the creation of reliable point-of-care (POC) diagnostic and monitoring appliances, including lab-on-a-chip type devices in the next steps of development. The test results show the good working ability of the developed analyzer; however, also limitations and problems that require attention and further improvement are appointed.

30 June 2019 in Micromachines
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Journal Article
Open access
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Tamás PardyTamás Pardy
Tamás Pardy
HSHenri Sink
Henri Sink
AKAnts Koel
Ants Koel
TRToomas Rang
Toomas Rang
Nucleic acid amplification tests (NAAT) are widely used for the detection of living organisms, recently applied in Lab-on-a-Chip (LoC) devices to make portable DNA analysis platforms. While portable LoC-NAAT can provide definitive test results on the spot, it requires specialized temperature control equipment. This work focuses on delivering a generalized low-cost, wireless smart thermostat for isothermal NAAT protocols in 2 cm × 3 cm LoC cartridges. We report on the design, prototyping, and evaluation results of our smart thermostat. The thermostat was evaluated by experimental and simulated thermal analysis using 3D printed LoC cartridges, in order to verify its applicability to various isothermal NAAT protocols. Furthermore, it was tested at the boundaries of its operating ambient temperature range as well as its battery life was evaluated. The prototype thermostat was proven functional in 20–30 °C ambient range, capable of maintaining the required reaction temperature of 12 isothermal NAAT protocols with 0.7 °C steady-state error in the worst case.

18 June 2019 in Sensors
Verified
Journal Article
Open access
PDF file
MRMuhammad Rashid
Muhammad Rashid
AKAnts Koel
Ants Koel
TRToomas Rang
Toomas Rang
Over the last decade graphene based electronic devices have attracted the interest of researchers due to their exceptional chemical, electrical and optical properties. Graphene is very sensitive to any physical changes in its surrounding environment and, inherently, has very low electronic noise. This property of graphene makes it a suitable candidate for sensor applications. The purpose of the work presented in this article is to demonstrate the ability of graphene derivatives to detect toxic organic compounds like phenol and methanol. A novel method for the detection of organic compounds (phenol and methanol) has been introduced in this article. In this method, a change in the photocurrent, as well as electric current, have been used as detection signals to improve the sensor accuracy and selectivity for specific target molecules. A nanoscale electronic device simulator, Quantumwise Atomistix Toolkit (ATK), has been used to simulate graphene nanosheet and armchair graphene nanoribbon based sensors. Devices density of states (DOS), current–voltage curves and photocurrent curves have been calculated with the ATK simulator. In the proximity of target molecules, a significant change in DOS, electric current and photocurrent have been observed. The simulated graphene based structures can be converted into physical sensors to obtain a low cost, small sized, integrated sensing device.

23 March 2021 in Micromachines
Verified
Journal Article
Open access
PDF file
KPKaiser Pärnamets
Kaiser Pärnamets
Tamás PardyTamás Pardy
Tamás Pardy
AKAnts Koel
Ants Koel
TRToomas Rang
Toomas Rang
OSOtt Scheler
Ott Scheler
FAFariha Afrin
Fariha Afrin
High-throughput microflow cytometry has become a focal point of research in recent years. In particular, droplet microflow cytometry (DMFC) enables the analysis of cells reacting to different stimuli in chemical isolation due to each droplet acting as an isolated microreactor. Furthermore, at high flow rates, the droplets allow massive parallelization, further increasing the throughput of droplets. However, this novel methodology poses unique challenges related to commonly used fluorometry and fluorescent microscopy techniques. We review the optical sensor technology and light sources applicable to DMFC, as well as analyze the challenges and advantages of each option, primarily focusing on electronics. An analysis of low-cost and/or sufficiently compact systems that can be incorporated into portable devices is also presented.