Monthly Archives: July 2023

3-D Printed Electronics

Today, 3-D printing is the most popular technology among all manufacturing and prototyping methods. However, 3-D printing is not new. In the 1980s, a company filed a patent for 3-D constructing models using stereolithography. Such patents have been instrumental in holding back the development, manufacture, and distribution of 3-D printing technology, until now.

3-D printing typically works by slicing a 3-D design into several small horizontal 2-D sections and then splicing them together by printing each 2-D slice atop the other. 3-D printers commonly use a thermoplastic wire wound on a reel. The printer extrudes this wire through a hot nozzle. There are 3-D printers that build models from paper. They cut out each layer from the paper, and glue one layer to the next. Other, more advanced systems sinter metallic dust using lasers.

It is possible to use 3-D printing technology for manufacturing electronic components. This uses a printer and an additive process. However, not all see the 20-D printed electronics as being actually 3-D printed. For instance, although they consider transistors as 2-D, in actual practice, they are 3-D, requiring both additive and subtractive processes to build up their insulating layers, source and gate terminals.

For now, there is little practical application for most 3-D printed electronics, and their use in the real world is rare. This is so because manufacturing electronics in the traditional manner is much easier, cheaper, and more reliable. Still, there is a significant amount of research for trying and creating practical devices with 3-D printing technology. So far, there has been significant success in printing transistors, capacitors, diodes, and resistors using 3-D processes.

Although electronic components may use several materials, 3-D printed devices generally use graphene or other organic polymers. Researchers use graphene, as it gives them the ability to create narrow channels and gates while allowing doping. It is easy to dispense organic polymers in solution form, which is ideal for using them in inkjet printers.

However, with printed electronic capabilities still far removed from standard electronic systems, it is rare to find commercial applications for printed electronics. However, there is plenty of research going into printing them.

Being still in their infancy, printed electronics are presently found only in research labs, or in prototypes. There are two technologies popular, tending towards practical—Pragmatic and Duke University.

A UK-based company, Pragmatic, produces printed electronic components for one-time applications. These are disposable electronic items like RFID tags. The most significant feature of Pragmatic devices is they use a flexible substrate. They cover all essential components like resistors, capacitors, and transistors. Although Pragmatic has not fully demonstrated a functional device, they have produced ARM core processes, claiming each device consumes 21 mW and energy efficiency of 1%.

Presenting the best examples of practical printed electronics, Duke University claims its products exceed the typical life cycle. They use a new method of additive processes for creating printed electronic components like resistors, capacitors, and transistors. Their components are mostly based on carbon, while the construction uses aerosol spraying similar to inkjet technology. They build the insulating layers from cellulose.

Modern Smoke Safety Sensors

The CN-0537 is a modern smoke detector with a design complying with the specifications outlined in UL 217. The design is based on fire data that researchers have collected at the smoke testing facilities of the Underwriters Laboratories and Intertek Group plc. The design uses the integrated optical sensor ADPD188BI and an optimized smoke chamber. It has a single calibrated device for sensing and measuring smoke particles. 

The design also uses a smoke detection algorithm that UL has tested and verified. This facilitates OEMs in reducing their product development time and thereby delivering their product designs more quickly.  The hardware design has a form factor resembling the Arduino board, and this includes an ADICUP3029 microcontroller development board apart from the CN-0537 smoke detector.

There are two basic designs popular for smoke detectors. One is the ionization type which uses radioactive materials to ionize the air while checking for electrical imbalances. The other is the photoelectric type that checks for current in the photodetector caused by light reflecting off airborne smoke particles and falling on the photodiode.

Although experts recommend a combined solution of both types, the improved reliability of the photoelectric smoke detector makes it more popular. It is faster in detecting common house fires and has a smaller response time to smoldering fires.

The optical module ADPD188BI is a complete photometric system. Its design is specifically meant for smoke detection applications. Rather than the conventional discrete smoke detector circuits, using the ADPD188BI makes the design significantly simpler. This is because the integrated package contains two LEDs and two photodiodes, along with an analog front end. The module utilizes a double-wavelength technique. The two LEDs emit light at different wavelengths—blue light at 470 nm, and infrared light at 850 nm. The LEDs also pulse at two independent time slots, and any particulate matter present in the air scatters the transmitted light back into the device.

The scattered light reaches two integrated photodiodes, which produce proportional levels of current. The analog front electronics digitize this output current. As the optical power from the LEDs is maintained constant, any increase in the ADPD188BI output over time indicates that airborne particles are building up.

The response of the ADPD188BI photometric sensor is a ratio of the input optical power to the transmitted optical power. The manufacturers refer to this as the power transfer ratio or PTR and express it as nW/mW. PTR is a more meaningful parameter than the raw output, as it is independent of the actual hardware settings.

The ambient temperature affects the response of the ADPD188BI system. As the shape of the temperature response curve can vary for the blue LED depending on the amount of current in the LED, it complicates matters further. The temperature response curve of the infrared LED is independent of the LED current.

The CN-0537 smoke detector has a temperature and humidity sensor that monitors the conditions, in real-time, within the chamber right next to the optical module ADPD188BI. This helps to determine the value of the relative response. The software helps with temperature compensation.

Protecting the Li-ion Battery

For decentralization of the source of energy, it is hard to beat rechargeable lithium-ion batteries. A wide range of applications uses this electrochemical option of energy storage as a strategic imperative. That includes powering up units in the military sector,  storing and providing energy for personal use, keeping uninterruptible power supply systems operational for data centers and hospitals, storing energy from photovoltaic systems, and enabling the operation of battery electric vehicles and power tools.

The rechargeable battery pack is the most common design in the accumulator segment and accounts for the major share of battery-powered applications. Such a pack usually consists of multiple Li-ion cells. With continuous technological development, the economics of the Li-ion rechargeable battery pack is also becoming attractive enough to warrant a substantial increase in its use. This is also leading to the miniaturization of individual cells, resulting in an increase in their energy density.

However, even with the increased availability and use, the Li-ion rechargeable battery pack continues to carry a residual risk of hazards, especially due to the increase in energy density brought on by miniaturization. The disadvantage is in terms of safety.

The electrolyte in the Li-ion cells is typically a mixture of organic solvents and a conductive salt that improves its electrical conductivity. Unfortunately, this also makes the mixture highly flammable. During operation, the presence of an inordinate thermal load can lead to the point where the mixture becomes explosive. Furthermore, this safety hazard to the end-user is increasing with the constant efforts to further increase the energy density of Li-ion cells.

Most electric battery cells have a narrow operational temperature range, varying from +15 °C to +45 °C. That makes temperature the key parameter. When the cell exceeds this temperature range, its rising heat becomes a threat to its functional safety, and to the safety of the overall system.

Overcharging the battery substantially increases the statistical probability of the defect in the cell. This may lead to a breakdown of the cell structure, typically associated with the generation of fire and in some cases, an explosion.

Manufacturers of rechargeable battery packs try to mitigate this risk by including a battery management system, and primary and secondary protection circuits that they embed in the electronic safety architecture of the battery. This allows the battery to remain within its specified operating range during the charging and discharging cycles. But nothing is immune to failure, including components in the protection circuit, and the battery system can ignite and explode on an excessively high load.

As the battery powers up a load, excessive current flow can heat up the battery, and the primary protection circuit may not detect it even when it exceeds the permissible level. For the protection of batteries, RUAG Ammotec is offering a heat lock element, a pyrotechnical switch-off device that is entirely independent of the battery system. This comprises a physicochemical sensor to continuously monitor the environmental heat. As the temperature rises, the sensor blocks the flow of current permanently. The heat lock element causes an insulating piston to shear off a current conductor, thereby electrically isolating the battery.

Are We Ready for 6G?

Apart from simply being an evolution of the 5G technology, 6G is actually a transformation of cellular technology. Just like 4G introduced us to the mobile Internet, and 5G helped to expand cellular communications beyond the customary cell phones, with 6G the world will be taken to newer heights of mobile communications, beyond the traditional devices and applications for cellular communication.

6G devices operate at sub-terahertz or sub-THz frequencies with wide bandwidths. That means 6G opens up the possibility of transfers of massive amounts of information compared to those under use by 4G and even 5G. Therefore, 6G frequencies and bandwidth will provide applications with immersive holograms with VR or Virtual Reality and AR or Augmented Reality.

However, working at sub-THz frequencies means newer research and understanding of material properties, antennas, and semiconductors, along with newer DSP or Digital Signal Processing technologies. Researchers are working with materials like SiGe or Silicon Germanium and InP or Indium Phosphide to develop highly integrated high-power devices. Many commercial entities, universities, and defense industries have been going ahead with research on using these compound semiconductor technologies for years. Their goal is to improve the upper limits of frequency and performance in areas like linearity and noise. It is essential for the industry to understand the system performance before they can commercialize these materials for use in 6G systems.

As the demand increases for higher data rates, the industry moves towards higher frequencies, because of the higher tranches of bandwidth availability. This has been a continuous trend across all generations of cellular technology. For instance, 5G has expanded into bands between 24 and 71 GHz. 6G research is also likely to take the same path. For instance, commercial systems are already using bands from FR2 or Frequency Range 2. The demand for high data rates is at the root of all this trend-setting.

6G devices working at sub-THz frequencies require generating adequate amounts of power for overcoming higher propagation losses and semiconductor limits. Their antenna design must integrate with both the receiver and the transmitter. The receiver design must offer the lowest possible noise figures. The entire available band must have high-fidelity modulation. Digital signal processing must be high-speed to accommodate high data rates in wide bandwidth swathes.

While focussing on the above aspects, it is also necessary to overcome the physical barriers of material properties while reducing noise in the system. This requires the development of newer technologies that not only work at high frequencies, but also provide digitization, test, and measurements at those frequencies. For instance, handling research at sub-THz systems requires wide bandwidth test instruments.

A 6G working system may require characterization of the channel through which its signals propagate. This is because the sub-THz region for 6G has novel frequency bands for effective communications. Such channel-sounding characterization is necessary to create a mathematical model of the radio channel that can encompass intercity reflectors such as buildings, cars, and people. This helps to design the rest of the transceiver technology. It also includes modulation and encoding schemes for forward error correction and overcoming channel variations.

Why are VFDs Popular?

The industrial space witnesses many innovations today. This is possible due to easily affordable and available semiconductors of various types, which makes it easier for manufacturers. One of the most popular innovations is the VFD or variable frequency drive.

Earlier, a prime mover had only a fixed speed, and its use was limited to expensive, non-efficient devices. With the advent of VFDs, it was possible to have an easy, efficient, cost-effective, and low-maintenance method of controlling the speed of the prime mover. This addition to the control of a prime mover not only increases the efficiency of the operation of equipment but also improves automation.

OEMs typically use VFDs for small and mobile equipment. They only need to plug it into a commercial single-phase outlet, in the absence of a three-phase power supply. These can be hose crimpers, mobile pumping units, lifts, fans/blowers, actuator-driven devices, or any other application that uses a motor as the prime mover. Using a VFD to vary the motor’s speed could improve the operation of the equipment. Apart from the benefits of variable speed, OEMs also use VFDs because of their ability to use the single-phase power source to output a three-phase supply to run the motor.

Although the above may not seem much, the value addition is tremendous, especially for the production of small-batch items. As VFDs output three-phase power, they can use standard three-phase induction motors, which are both widely available and cost-effective. VFDs also offer current control. This not only improves motor control but also helps in avoiding inrush currents that are typical when starting induction motors.

For instance, a standard duplex 120V 15A power source can safely operate a 0.75 HP motor without tripping. However, a VFD, when operating from the same power source, can comfortably operate a 1.5 HP motor. In such situations, using a VFD for doubling the prime mover power has obvious benefits for the capacity or functionality of the application.

The above benefits make VFDs an ideal method of controlling motors for small OEM applications. VFD manufacturers also recognize these benefits, and they are adding features to augment them. For instance, they are now adding configurable/additional inputs and outputs, basic logic controls, and integrated motion control programming platforms to VFDs. This is making VFDs an ideal platform for operating equipment and controlling the motor speed, thereby eliminating any requirement for onboard microcontrollers.

However, despite several benefits, VFDs also have some limitations. OEMs typically face problems when using GFCI or ground fault circuit interrupter breakers with VFDs. A GFCI typically monitors current flowing through the ground conductor. Leakage currents through the ground conductor can electrocute users.

A VFD consists of an inverter stage that works on high-frequencies. Harmonics from this stage can create ground currents, also known as common-mode noise. The three-phase waveforms generated by the inverter do not always sum to zero (as is the case in a regular three-phase power source), leading to a difference of potential causing capacitive induced currents. When these currents seek a path to the ground, they can trip a GFCI device. However, this can be minimized by lowering the operating frequency.

What is Pressure and How to Measure it?

The concept of pressure is simple—it is a force. Typically measured in psi or pounds per square inch, pressure is the force applied on a specific area. However, there are other ways of expressing pressure and different units of pressure measurement. It is important to understand the differences so that the user can apply specific measurements and units properly.

Depending on the application, there are several types of pressure. For instance, there is absolute pressure. Engineers define the zero point of absolute pressure as that occurring in a perfect vacuum, which is the case for some applications. Absolute pressure readings typically include the pressure of the media added to the pressure of the atmosphere. One can use the absolute pressure sensor to rely on a specific pressure range for reference while eliminating instances of varying atmospheric pressure. Thermodynamic equations and relations typically use absolute pressure.

Then there is gauge pressure, which indicates the difference between the pressure of the media and a reference. While the pressure of the media can be that of the gas or fluid in a container, the reference can be the local atmospheric pressure. For instance, the gauge for measuring tire pressure will read zero when disconnected from the tire. Which means, it will not read or register the atmospheric pressure. However, when connected to the tire, it can reveal the air pressure inside the tire.

Another type of pressure is the differential pressure. It is somewhat more complex compared to gauge or absolute pressure, as it is the difference in the pressures of two media. The gauge pressure can also be termed as a differential pressure sensor, as it measures the difference between the atmospheric and the media’s pressure. With a true differential pressure sensor, one can measure the difference between any two separate physical areas. For instance, by measuring the differential pressure, one can indicate the pressure drop or loss, from one side of a baffle to the other.

Compared to the above three, sealed pressure is less common. However, it is useful as a means of measurement. It measures the pressure of a media compared to a sample of atmospheric pressure that is sealed hermetically within a transducer. Exposing the pressure port of the sensor to the atmosphere will cause the transducer to indicate a reading close to zero. This is due to the presence of ambient atmospheric pressure on one side of the diaphragm and a fixed atmospheric pressure on the other. As they are nearly the same, the reading it indicates is close to zero. When they differ, the reading will be a net output other than zero.

The internal pressure can change due to differences in temperature. This may create errors exceeding the accuracy of the sensor. This is the main reason engineers use sealed sensors for measuring high pressures—the changes in the references cause only small errors that do not affect the readings much.

Engineers typically use several units when expressing measurements of pressure. They are easy to modify using the conventions of the International System of Units, even when they are not a part of that measurement system.

Difference Between FPGA and Microcontroller

Field Programmable Grid Arrays or FPGAs do share some similarities with microcontrollers. However, the two are different. While both are integrated circuits, and products and devices use them, there is a distinct difference between the two.

It is possible to program both FPGA and microcontrollers such that they perform specific tasks. However, they are useful in different applications. While FPGA users can program them straight away, it is possible to program microcontrollers only when in a circuit. Another difference between the two is FPGAs are capable of handling multiple parallel inputs, while microcontrollers can read only one line of code at a time.

As FPGAs enable a higher level of customization, they are more expensive and also more difficult to program. On the other hand, microcontrollers, being small and cost-effective, are also easy to customize. It is necessary to know the differences and similarities between the two to make an informed decision about which of them to effectively use for a project.

A microcontroller is typically an integrated circuit that functions like a small computer, constituting a CPU or central processing unit, some amount of random access memory or RAM, and some level of input/output devices. However, unlike a desktop computer, a microcontroller is incapable of running numerous programs. A microcontroller, being a special-purpose device, is capable of executing only one program at a time.

It is possible to make a microcontroller perform a single function repeatedly or at intervals of user request. Typically embedded along with other devices, microcontrollers can be a part of the appliance, no matter the type of product. Moreover, these small computers can operate at very low energy levels—most consume currents in milliamperes, at typically 5 VDC or lower. When produced in large quantities, microcontrollers can be very affordable, although the appliance where the microcontroller is embedded can vary in cost.

On the other hand, an FPGA is a much more complicated device compared to a microcontroller. Most FPGAs come with a pre-programmed chip that allows the users to change the software but not the hardware inside it. By changing the software, users can configure the hardware while using the FPGA. Embedded within a device, an FPGA allows altering the hardware of the device without adding or removing anything physically.

An FPGA is typically an array of integrated circuits, with the arrays arranged in programmable logic blocks. A new FPGA is not configured in any particular function. Users decide the configuration according to their application, and if necessary, users can reconfigure the FPGA as many times as necessary. The FPGA configuration process requires the use of a Hardware Description Language, or HDL, such as Verilog and VHDL.

A modern FPGA features many logic gates and RAM blocks to enable it to execute complex computations. Components in an FPGA may include complete memory blocks in addition to simple flip-flops.

Both FPGAs and microcontrollers serve similar basic functions. Manufacturers develop these items such that users can decide their functionality when designing the application. Both integrated circuits have a similar appearance and are versatile, and users can apply them for various applications.

Difference Between IoT and Embedded Systems

Today, we are accustomed to using many IoT or Internet of Things and embedded systems every day. But just a decade ago, very few people had smartphones. Innovations and technological advancements have changed that—ushering in an era of the smart revolution almost globally. With the advent of the 4th Industrial Revolution and the revolutionary use of IoT equipment, several million devices link to the internet and cloud services. We can easily connect to the world around us, mainly due to IoT connectivity along with the evolution of regular gadgets. Many new equipment and devices now come inbuilt with IoT technologies, and these include not only personal fitness devices, but also kitchen items, home heating systems, and medical equipment.

Embedded systems typically comprise a small computer integrated into a mechanical or electrical system. Some examples of such devices include electric bikes, washing machines, home internet routers, and heart monitors. Each of these devices comes with an inbuilt computer that serves a specific purpose. Forming the brain of the device, the computers may have one or more microprocessors. For instance, a smartphone consists of many embedded systems interconnected to function simultaneously. So far, embedded systems hardly ever connect to larger networks such as the Internet. Most still use antiquated connection standards such as the RS-232 to interconnect to other embedded systems. These protocols are usually plagued with bandwidth and speed constraints. In comparison, modern communication protocol standards for embedded systems are much faster and support higher bandwidth. Many also support wireless connectivity. All in all, modern embedded systems are more sophisticated than before.

IoT devices, on the other hand, are rather pieces of hardware. They can be machines, appliances, gadgets, actuators, or sensors. Their main function is to transfer data over networks such as the Internet. The design of most IoT devices allows them to be useful for specific purposes. It is possible to integrate IoT devices into various appliances, including industrial machinery, medical equipment, environmental sensors, and mobile systems. There are IoT embedded systems also, and they are embedded systems that connect to the internet or other networks like home networks. Most are capable of carrying out tasks beyond the capabilities of the individual system. Connectivity allows them to perform functions that were not possible earlier.

Sensors effectively behave as the Internet of Things or IoT devices when they can transmit data over networks, including the Internet. It is possible for an embedded system to be enhanced with IoT capabilities by incorporating an IoT module. The basic IoT ecosystem roots still rely heavily on embedded systems. It is possible to gauge the importance of embedded systems within the IoT realm by the fact that embedded systems support much of the functionality of IoT devices.

Although a network, such as the Internet, is a necessary medium for transmitting data to and from IoT devices to their cloud services, embedded systems help in the actual collection, rationalization, interpretation, and transmission of the data from the sensor. Embedded systems also help interface the data with online services, smartphone applications, and nearby computers. In this chain, the numerous sensors that actually collect real-world data, remain the most important link.