Stretch Your Battery

Although there is no existence of a stretchable phone or laptop at present, researchers have developed a prototype of a battery that is wearable and can be stretched. This stretchable Lithium-ion battery is fabric-based. With this type of battery, the team of researchers, from the University of Houston, has opened up a new direction for the future of wearable technology.

Professor Haleh Ardebili first came up with the idea for this stretchable Li-ion battery. He initially envisioned a future with smart, interactive, and powered clothes. From here, it was but a natural step to create stretchable batteries that could integrate with stretchable devices and clothes. For instance, one can use clothes with interactive sensors embedded in them to monitor their health.

Typically, batteries are in general rigid and are a major bottleneck in the wearable technology development of the future. Not only does the stiffness of a battery lead to limited functionality, but their use of liquid electrolytes raises safety concerns. Especially as the organic liquid electrolyte is flammable and prone to explosions. The researchers are using conductive fabric made of silver as the platform for the flexible battery and as the current collector.

The team prefers the woven sliver fabric for the battery, as it can easily deform mechanically by stretching, while still providing the necessary electrical conduction pathways for the electrodes of the battery to perform. The battery electrodes need to allow the movement of both ions and electrodes. With their experiments and prototypes, the researchers have entered to investigate an unexplored field in science and engineering. Going beyond the prototype, the researchers are working on optimizing the design of the battery, its fabrication, and its materials.

According to the researchers, the fabric-based stretchable battery will work wonders for various applications like smart space suits and devices for interacting with humans at a variety of levels, such as consumer electronic equipment embedded in garments for monitoring health. In fact, the applications for such a device are endless, providing a path for light, safe, flexible, and stretchable batteries. However, the team feels they have much to do before they can commercialize their idea.

While they need to work on the cost and scale for commercial viability, the team feels there is a clear need in the market for such batteries, especially in the future, for stretchable electronic devices. Once such products appear in the market, there will be a huge demand for the batteries. Right now, the team wants to make sure the batteries are as safe as possible.

The team faced many challenges in designing the stretchable battery. It took more than five years for them to reach the present state. Their main impediment was integrating the fabric with a functional battery.

As to how the battery works, the team explained that while the electro-chemically active material in the battery provides charge through bonding and debonding of lithium, it coats and deposits on the sliver stretchable fabric. While the lithium ions shuttle back and forth within the battery between the positive and negative electrodes, the battery can stretch as the polymer electrolyte and the fabric can also do so.

Basics of Potentiometers

The electronics industry uses many resistance-based components. While in some of them, the resistance is fixed, for others, the user can change the resistance. Potentiometers fall in the second category. Very often, they have a mechanical arrangement that allows the user to change the resistance value manually. Unlike the fixed resistor type components, potentiometers act as variable resistors.

The most common use of a potentiometer is to divide an applied voltage. Therefore, these components serve a dual purpose. On one hand, they help to adjust the voltage output within the circuit, while on the other, they can accurately measure the electric potential. This is the reason for their name being potentiometer. The typical construction of a potentiometer has a resistive element with a wiper. Adjusting the position of the wiper on the resistive element allows the potentiometer to deliver a continuously variable voltage output as a signal on its wiper. It is necessary to add that potentiometers are passive components. That means, unlike active elements, potentiometers do not require additional circuitry or a power supply to operate.

According to physical laws, the resistance of an object depends on many factors, one of them being its length. With all other parameters remaining constant, the resistance of an object will vary directly as its length does. Therefore, two objects made of the same material, with the same cross-sectional area, will exhibit different resistances if their lengths vary. Potentiometers take advantage of this principle to exhibit adjustable output.

The industry uses two types of potentiometers—analog and digital. Our focus is primarily on analog potentiometers, of which there are again two types—linear and rotary. Both rely on mechanical arrangements to manipulate and control the output.

A potentiometer, whether linear or rotary, has a sliding contact that the user can move along a uniformly resistive element. Altering the position of this sliding contact results in its adjustable output. The slider actually modifies the path through which current flows in the potentiometer. With the input voltage applied across the entire length of the resistive element, the output voltage is available as a potential drop between one end of the resistive element and the sliding or rotating contact. By adjusting the position of the moving element along the resistive element, it is possible to determine the voltage applied to the next part of the circuit.

As the name suggests, linear potentiometers employ a straight-line or linear motion using a sliding mechanism for establishing contact with the resistive element. The linear motion adjusts the contact’s position on the resistive element and subsequently, the output voltage.

On the other hand, rotary potentiometers use angular movement. They have a shaft connected to a wiper. This wiper slides along a resistive element arranged circularly around the shaft. By turning a knob on the shaft, it is possible to change the position of the wiper, thereby altering the output. Other variants of the rotary potentiometers are also available, where an external tool can rotate the wiper, thereby eliminating the need for a shaft to be present.

What is the Raspberry Pi Pico?

The electronic industry uses embedded systems with powerful, low-cost MCUs or microcomputer units. This helps product development by adding capabilities like machine learning and rapid prototyping while supporting many types of tests. In most cases, the designer must understand the MCU in depth while also mastering low-level programming languages. Often, development boards are way too expensive, not readily available, and it may be difficult to get them up and running. As an alternative, designers can go for the Raspberry Pi Pico.

The Raspberry Pi Pico is a readily available, low-cost development board. It uses the RP2040 MCU which offers a wide range of capabilities to the designer. Additionally, it has many extension boards and software development kits that make the task of an embedded system designer easy.

First introduced in 2021, designers can use the Raspberry Pi Pico as a standalone development board. They can also integrate the board into a system by soldering the edge connectors onto a carrier board. The Pico is popular mainly because of its sub $5 cost, which is way less than the $20+ price of other similar development boards.

The RP2040 MCU that the Pico uses is a dual-core processor of the ARM Cortex family. It operates at 133 MHz. It includes 264 kB of SRAM and an external 2 MB flash chip interfacing with the MCU over a quad serial peripheral interface. A user LED, pushbutton, and crystal oscillator are on the board. The user can configure the pushbutton to boot the processor directly or direct it to a bootloader. They can use the crystal oscillator to act as a PLL or phase-locked loop for creating a high-speed CPU clock.

The Pi Pico offers an extensive ecosystem, where developers can use either the C or the MicroPython language to write applications for the board. In reality, there are three types of Pi Pico boards to choose from—the SC0915 with a standard configuration, the SC0197 with the header connectors, and the SC0918 with a low-cost Wi-Fi chip.

Each of the above boards has the same general footprint. The edge connectors are 40-pins providing connection options for peripherals. Among the connections available are those for power, ground, UART or universal asynchronous receiver and transmitter, GPIO or general purpose input and output, PWM or pulse width modulation, ADC or analog to digital converter, SPI or serial peripheral interface, I2C or inter-integrated circuit interface, and debugging.

There are several options for using the Pi Pico for rapid prototyping. One can use a breadboard and populate the headers, but this may result in a mess of wires. The other neater option is to use breakout boards to expand the edge connectors and make them available for easy interfacing.

The Raspberry Pi Pico ecosystem offers MicroPython as an alternative to the older C language. This is a modern language that most designers are already familiar with. They use API or application programming interfaces for accessing hardware and abstracting out the low-level details of the MCU and its related hardware.

What is Ultrasonic USoP?

USoP or Ultrasonic System-on-Patch are wearable patches with integrated electronic sensors. These autonomous wearable patches allow continuous tracking of physiological signals when worn on the body. They use ultrasonic methods to measure signals from tissues as deep as 164 mm inside the body. For instance, they can continuously monitor physiological signals like cardiac output, heart rate, and blood pressure for up to 12 hours at a time.

Developed by a team at the University of California at San Diego, these fully integrated wearable patches can monitor deep tissues using ultrasonic systems, especially for subjects on the go. The team has developed the technology for potentially life-saving cardiovascular monitoring. USoP is a major breakthrough for the team from one of the world’s leading ultrasonic wearable labs.

Giving a complex solution to the world of wearables with ultrasonic technology, the project not only has a wearable sensor but also has control electronics within the wearable form factor. This is a truly wearable device that can sense vital signals from deep tissues without the use of wires.

The USoP or ultrasonic system-on-patch is a fully integrated autonomous wearable that the lab has built on its previous work in soft ultrasonic sensor design. While all their earlier soft ultrasonic sensors required tethering cables for power and data transmissions, the USoP has a small and flexible control circuit for communicating with the ultrasonic transducer array, for collecting and transmitting data wirelessly. For tracking subjects in motion, it also has a machine-learning component that helps it to interpret the data.

According to the team, this technology has a huge potential for saving and improving lives. The sensor has the capability to evaluate cardiovascular function even while in motion. It can predict impending heart failure by detecting abnormal values of cardiac output and blood pressure, whether at rest or during exercise. In a healthy population, the device can monitor cardiovascular activity during exercise in real-time and provide insight into the actual workout intensity that each person exerts, thereby guiding the formulation of individual training plans.

The team discovered that their latest invention had more capabilities than they had initially anticipated during its development. Their initial aim was to develop a wireless blood pressure sensor. Later, as they were designing the circuit, the algorithm, and collecting clinical insights, they realized the system was capable of measuring many additional physiological parameters besides blood pressure, including arterial stiffness, cardiac output, expiratory volume, and much more. These additional parameters are essential for in-hospital monitoring or daily health care.

While moving forward, the team has plans for testing the sensor among a larger population. At present, they are in the process of working with clinicians from the university—for obtaining IRBs for approval for the clinical trials.

The USoP has considerable advantages over conventional ultrasonic machines, which are bulky and wired, and which require an experienced sonographer to perform the maneuvering of manual probes, while the subject must remain immobile. It is possible to train the machine-learning algorithm on one patient and apply it to many others, with minimal retraining.

All about Thermoelectrics

TECs or Thermoelectric coolers or Peltier coolers are typically made from semiconductor materials exhibiting good electrical conductivity and thermal insulation. One such material is Bismuth Telluride. It offers the best performance of the above properties at room temperature environments. The development of ceramic-based substrates along with advanced semiconductor processing in the 1960s made thermoelectric devices available in commercial quantities.

TECs are solid-state devices that pump heat from a hot region to a colder region. For this to function properly, a heat transfer mechanism is necessary, a sort of heat exchanger that can absorb and dissipate the heat. TECs typically require DC voltages to operate. When power is applied, current flows through the cooler, carrying electrons from one side of the ceramic to the other. This results in one side of the substrate cooling down, while the other remains hot.

With a standard single-stage TEC, it is possible to achieve a temperature differential of nearly 70 °C at room temperature. That means the temperature difference between the two sides of the TEC can reach a maximum of 70 °C. With more advanced materials, TECs can reach temperature differentials of 74 °C.

Compared to alternate cooling technologies, TECs offer several advantages. One of them is their compact form factor, making them ideal for applications involving low heat loads. As there are no moving parts, TECs operate for extended periods with almost no maintenance necessary.

While cooling with thermoelectric coolers, it is possible to reach temperatures well below the freezing point of water. For instance, with multistage coolers, it is possible to reach temperatures below -90 °C. One major advantage of TECs is their ability to reverse their polarity by reversing the direction of current flow. This property is very useful in enabling thermal cycling, resulting in precise control of temperature, up to ±0.01 °C, maintained under steady-state conditions.

TECs are very efficient for heating purposes as well. In fact, they are more effective compared to conventional resistive heaters. This is because the heat generated by TECs is from the input power in addition to the heat it pumps in from the cold side. As TECs do not emit any HCFCs, they are environmentally friendly.

Depending on their rated capacity, the footprint of a typical TEC can range from 2 x 2 mm to up to 62 x 62 mm. This makes thermoelectric coolers ideal for operating in tight geometric spaces such as in telecom, industrial, analytical, and medical applications. Compared to conventional technologies such as compressor-based systems, TECs are miniscule.

Applications that handle low heat loads, less than 400 W, and those requiring cooling below ambient temperatures are typical applications benefitting from TECs. Where the control temperature is near ambient, passive heat exchanger solutions utilizing a heat sink and a fan may be adequate. Design engineers typically use TECs when their design criteria include such factors as high reliability, precise temperature control, compact form factor, minimal global warming potentials, and low weight requirements. TECs are ideal for various medical, telecom, analytical, and industrial applications that require active cooling.

Hall Effect Sensors for Position Selection

User systems often require the detection of position for operating in a specific switch mode. Such type of On or Off functionality is a straightforward requirement and many devices implement it with Hall-effect switches, including power tools, light switches, safety harnesses, and laptop lids.

The output of the sensor toggles its state as soon as the input magnetic field crosses the operating threshold. Likewise, the output reverts to the idle state when the magnitude of the magnetic field reduces below the release threshold. Hysteresis built into the device prevents the output from toggling rapidly where the magnitude of the magnetic field is close to the operating threshold.

Many applications use this functionality. For typical cases, two output states are adequate, thereby helping to reduce mechanical wear and preventing interference from grease and dust.

Although two positions may be adequate for detection in many applications, others require the detection of additional states. For instance, a tool may require a three-position power switch, denoting Off, Low, and High power modes. Detecting all three states is difficult using a single sensor. Initially, it may seem possible by adding a sensor for every switch position in the system.

A unipolar switch is well-suited for such an application. The designer places the magnet very close—so the air gap is small—thereby ensuring the pole of the magnet facing the sensor will always exceed the worst-case operating point. When the magnet is above the sensor, it results in an upwardly directed field vector. When the magnet has traveled greater than its own width, the sensor will not activate, as the direction of the field is now downwardly directed. Therefore, there can be an array of sensors representing any number of positions, provided the sensor spacing exceeds the full width of the magnet.

While the above arrangement is convenient for a low number of positions, the number of components required gets more difficult to manage as the number of positions increases. For such arrangements, dual-unipolar switches are more convenient.

Texas Instruments offers a dual-unipolar switch, DRV5032DU. It has two independently operating outputs. Each output is sensitive to an opposite polarity of the magnetic field. Where one sensor responds as it nears a North pole, the other will respond as it nears a South pole. This functionality allows the detection of three positions with a single magnet.

With the magnet mid-way between the two sensors, there is no component of the magnetic field available to activate the sensors, and therefore, both sensors remain deactivated. When the magnet moves to the left, it activates the N pole-sensitive output. Likewise, when the magnet moves to the right, the S pole-sensitive output activates. However, for this arrangement to function correctly, the magnet must have a length two times the distance of travel between the switch positions. When the magnet moves by one-half its length, one of its poles is directly above the sensor, thereby activating it.

Extending this format makes it possible to sense more than three positions. It requires an array of sensors spaced appropriately for creating additional unique positions.

Matter and Simplicity Studio

So far, home automation has always meant selecting an appropriate ecosystem. Well, that is a thing of the past now, as all IoT or Internet of Things devices can intercommunicate with this new, open-source protocol. Now designers can develop small demo applications that are Matter-compatible, and they can use the new Matter Development board, the SparkFun Thing Plus, and the Simplicity Studio IDE from the Silicon Labs.

Until now, multiple communication protocols have kept IoT devices a rather scattered lot. Developers and consumers were forced to decide how to make their devices communicate and lock them into that environment. With the introduction of Matter, however, those are days of the past, as Matter is a unified, open-source application-layer connectivity standard. Apart from increasing the connectivity among connected home devices, Matter allows the building of reliable and secure ecosystems.

In 2019, major and competing players such as Zigbee Alliance, Google, Apple, Amazon, and a host of other companies such as Nordic Semiconductors got together to develop a single communication protocol. Their aim was to unify the entire world of the Internet of Things. The result was Matter, a royalty-free, open-source protocol that allows devices to communicate over Thread, Bluetooth Low Energy, and Wi-Fi networks. Therefore, Matter-certified devices can communicate with each other regardless of the wireless technology they use, and do so seamlessly.

Now, there is no need for consumers, manufacturers, and developers to have to choose between Google’s Weave, Amazon’s Alexa, or Apple’s Homekit components. While for consumers, this represents increased compatibility, for manufacturers, it means simplified development.

The major benefit of Matter is it simplifies the management and setup of smart home devices. End-users can now set up their smart home systems easily and quickly, using Matter-certified devices. They will not need any technical skills or specialized knowledge. With the protocol supporting end-to-end encryption, safety is in-built, ensuring secure data transmission between devices.

However, this does not mean designers have been relegated to the role of consumers. The Sparkfun Thing Plus Matter Development Board from Sparkfun Electronics combines Matter and the Sparkfun Qwiic ecosystem, thereby providing an agile development and prototyping arrangement for designers of Matter-based IoT devices.

Silicon Labs offers its MGM240P wireless module for a secure 802.15.4 connectivity for both Bluetooth Low Energy 5.3 and Mesh (Thread) protocols. This module is available and ready for integration into the Matter IoT protocol for home automation. Moreover, the Thing Plus development boards are compatible with Feather, and include a Qwiic connector, thereby allowing easy integration for solderless I2C circuits.

Designers can download the latest Simplicity Studio from the Silicon Labs website, for the specific operating system they are using. It may be necessary to create an account for the download. After installing and running Simplicity Studio for the first time, the Installation Manager will come up, and search for any updates available. After updating, the Simplicity Studio will operate as the latest version.

In the next step, the Installation Manager will ask to install the devices by either connecting them or by defining the technology they use. The Installation Manager may want to install additional required packages before proceeding.

Happy Thanksgiving!

To allow our hard-working office staff the ability to spend time with their families during Thanksgiving week, we are closing our office from Monday, November 20 – Friday, November 24. During this time, we will still be shipping orders but phones will not be answered and emails will not be responded to until Monday, November 27th.

We eagerly anticipate serving you again when we reopen on Monday morning, November 27, ready to assist with your electronic component needs. Wishing you a joyous and peaceful Thanksgiving!

West Florida Components Thanksgiving week office hours

Difference Between Power and RF Inductors

In many electronic designs, we have components that consist of only several turns of a wire, with or without a core. These components are inductors. It is customary to find them in many types of electronic devices, including voltage and power conversion circuits to high-frequency microwave and RF circuits. Typically, inductors resist any change in the current flowing through them, by producing an electromagnetic field.

Available in a variety of package styles depending on their current ratings, inductors are essential components in electronic designs. They function as filters, chokes, and impedance-matching functions. For a practical application, it is essential to understand the important performance parameters of inductors.

Any inductor, whether used for power or RF applications, has the same performance parameters. These include the inductance value, its tolerance, current rating, its DC resistance, SRF or self-resonant frequency, Q or quality factor, and temperature range. However, specific applications may stress more on some of these performance parameters as they have more relevance for that application. For instance, an application involving RF frequencies may give more importance to Q and SRF parameters rather than to the current rating, which is more important for power applications.

The size of an inductor—how big or how small it can be—is usually dependent on the inductance value, its current carrying capacity, and acceptable losses. These are critical parameters when selecting inductors. Selecting an inductor usually begins with the inductance value, typically in nH or in mH, and depends on its function in the circuit. Associated with the nominal inductance value is its tolerance, in %, characterizing the amount of variation of the inductance value, and is determined by the application.

For instance, RF applications typically require inductances closely matched by precise inductance values, and with tight tolerances, such as ±2%. On the other hand, power applications may use inductors with inductance values within a larger band, and with wider tolerances, such as ±20%.

Another important parameter for inductors is their ability to handle current, which can vary greatly by application. This is specifically true for inductors in power circuits such as DC-DC converters, where the current values can change widely, with very high peak-to-average current ratios. Inductors selected on the basis of the application’s highest instantaneous current value may provide an inductor much larger than necessary. On the other hand, selecting an inductor based on the average current value in the circuit may lead to a small inductor resulting in inconsistent performance during peak current deliveries.

The quality of an inductor has more relevance in RF circuits than it has for power applications. Quality or the Q factor is a dimensionless parameter that characterizes the inductor’s bandwidth relative to its center frequency. High Q values are typically matched to narrow bandwidths and low losses, more critical in RF applications.

For power applications, the losses in inductors are more important. Here, the DC losses, characterized by the resistance of the wire, are rather more relevant. Therefore, inductors for power applications tend to be made of wires with larger diameters, so as to increase the area for current travel and thereby reduce the resistance.

Difference Between Chokes and Inductors

Industries typically use chokes and inductors for altering, filtering, and delivering electrical current. However, for using these devices effectively for machinery and devices that rely on electrical power, it is essential to understand the difference between chokes and inductors, as the design of these electrical components must meet specific applications’ requirements.

Despite a choke being a type of inductor, it has a design, functionality, and application that sets it apart from other inductor designs. Physically, this electrical component looks like a donut-shaped core and has an insulated wire wrapped around it.

As its name implies, primarily, a choke restricts or cuts off high-frequency components from alternating currents flowing through it. It allows only low-frequency currents, including direct currents to pass through. Therefore, a choke eliminates most of the high-frequency currents and allows only low-frequency and DC currents to pass through to the load.

Another function of the choke is its ability to restrict a steep rise and fall of current and voltage in circuits. A fast rise in voltage can damage insulation. Conversely, a choke can also generate high voltages such as those necessary to strike an arc for starting fluorescent tubes.

On the other hand, inductors primarily store electrical energy as a magnetic field when current passes through them. For this purpose, inductors typically have a magnetic core wrapped with an insulated coil. Therefore, all chokes are inductors, but the reverse is not true—not all inductors are chokes. Many technologies use inductors for various functions.

For instance, inductors are necessary to filter a band of frequencies by increasing the impedance for these frequencies. Inductors also act as proximity sensors without making physical contact, as the magnetic fields of the inductor and the object can interact. Multiple inductors, using the same magnetic field, constitute a transformer that can effectively transform, or step-up or step-down voltages. Inductors typically arranged circularly around a motor shaft, can interact with other stationary inductors to provide the torque necessary to rotate the motor shaft. Switching power supplies use inductors to temporarily store and supply electrical energy in and from their magnetic fields.

An inductor has a much wider functionality as compared to a choke. For instance, an inductor acts as a choke when filtering high-frequency signals. While the choke’s primary function is to remove high-frequency signals and allow low-frequencies and DC signals to pass through, the primary function of an inductor is to store energy in its magnetic field.

In RF circuits, a choke typically protects against the ingress of high-frequency signals, assuring operational stability. On the other hand, an inductor, in parallel or in series with a capacitor can act as a tuned circuit. Such tuned circuits allow the RF circuit to oscillate at a specific band of frequencies as determined by the inductor and capacitor combination.

Both chokes and inductors are critical in circuits that must conform to EMI/EMC or electromagnetic interference and compatibility standards. They block the generation and reception of unwanted signal frequencies in equipment. They prevent the electromagnetic spectrum of the device from increasing beyond a specified level as directed by the standards.