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This design based on an SR latch and two RC networks is, unlike many alternative solutions, neither complex nor expensive.

Single and differential capacitance sensors are widely used to measure linear and angle displacement, pressure, proximity, humidity, fluid level, inclination and acceleration. Both analog and digital circuits are used to interface the sensors (References 1-4). Some of the solutions tend to be complex and expensive (References 5-9).

Wow the engineering world with your unique design: Design Ideas Submission Guide

This Design Idea presents a very simple circuit to interface differential capacitance sensors (Figure 1). It is a relaxation oscillator made of an SR latch and two RC networks. When one of the capacitors is gradually charged through the corresponding resistor, the other capacitor is quickly discharged through a parallel switch. When the charging capacitor reaches the trip voltage VT of its gate, the latch changes its state. The other capacitor starts charging and the first one is quickly discharged. When the second charging capacitor reaches the trip level VT of its gate, the latch flips again returning to the initial state. The charge-discharge process repeats over and over again.

Figure 1 The sensor becomes part of a relaxation oscillator where one of the capacitors is charging when the other one is shorted; the two capacitors periodically swap their operation.

Signal VQ1 goes to a microcontroller, which measures time intervals t1 and t2 and calculates the average value VAVR = VDD * t1 / (t1 + t2). A number needs to be subtracted from this value so when the two capacitors are equal the average value is zero. Thus, the average value will be positive when C1 > C2 and negative when C1 < C2.

Circuit operation was tested with a bank of ten 50-pF capacitors. The left side of Figure 2 shows connections to set a duty cycle of 20%; the right side of the figure sets the duty cycle of 90%.

Figure 2 Sensor operation is simulated with a bank of 10 capacitors.

Figure 3 presents how period T and duty cycle D = t1 / T depend on the value of C1. Period barely changes between 96 and 98 µs, while the duty cycle is proportional to C1. A straight line fits perfectly the duty cycle data (the R2 factor equals 1); however, as Figure 4 shows, the line has a nonlinearity error of ±0.3%.

Figure 3 Circuit responses: at the top, the period is almost the same, below it, the duty cycle depends linearly on the value of C1.

Figure 4 The duty cycle response has a nonlinearity error of ±0.3 %.

The bump shape of the error graph means that a second-order polynomial may improve linearity. Indeed, equation y = 1*10-5 * x2 + 0.182 * x + 4.21 reduces the error down to ±0.1%. Such an equation is easy to implement in the microcontroller firmware.

Jordan Dimitrov is an electrical engineer & PhD with 40 years of experience. Currently, he teaches electrical and electronics courses at a Toronto community college.

Related Content

• From gap to signal: Non-contact capacitive displacement sensors
• Fundamentals in motion: Accelerometers demystified
• An introduction to capacitive sensing

References

1. Regtien P., E. Dertien. Sensors for mechatronics. 2nd ed., Ch. 5, Elsevier, 2018.
2. Northrop R. B. Introduction to instrumentation and measurement. 3rd ed., CRC Press, 2014.
3. Baxter L. Capacitive sensors. http://www.capsense.com/capsense-wp.pdf
4. Differential capacitance pressure sensor circuit. https://instrumentationtools.com/differential-capacitance-pressure-sensor-circuit/
5. Reverter F., O. Casas. Direct interface circuit for differential capacitive sensors. I2MTC 2008 – IEEE International Instrumentation and Measurement Technology Conference, Victoria, Vancouver Island, Canada, May 12-15, 2008.
6. Barile G. et al. Linear integrated interface for automatic differential capacitive sensing. Proceedings 2017, 1, 592.
7. Ferri G. et al. Automatic bridge-based interface for differential capacitive full sensing. 30th Eurosensors Conference, EUROSENSORS 2016. Procedia Engineering 168 (2016) 1585 – 1588.
8. Bai Y. et al. Absolute position sensing based on a robust differential capacitive sensor with a grounded shield window. Sensors (Basel). 2016 May; 16(5): 680. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4883371/
9. De Marcellis A., C. Reig, M. Cubells-Beltrán. A capacitance-to-time converter-based electronic interface for differential capacitive sensors. MDPI Electronics, Jan 2019.

The post Simple circuit interfaces differential capacitance sensor appeared first on EDN.

Munich, April 21, 2026 — The power electronics market is being driven by stricter efficiency targets, higher power densities, and increasing integration with large-scale power grids. Consequently, engineers must cope with non-ideal component behavior, fast transient stresses on wide-bandgap devices, and ever more demanding EMC requirements. The conference will address these challenges by presenting measurement-centric solutions that can be implemented with modern oscilloscopes, vector network analyzers, and precision power analyzers.

The program opens on May 5 with a keynote by Tobias Keller (Hitachi Energy) entitled “Power Semiconductors: Shaping the Future Power Grid – Performance and Reliability for Future Decades”. Tobias Keller will discuss the qualification of silicon and silicon carbide (SiC) devices for high-voltage grid applications, focusing on thermal cycling, short-circuit robustness, and long-term reliability data.

A second keynote, delivered on May 6 by Veit Hellwig (Infineon Technologies), will examine the impact of gallium-nitride (GaN) technology on high-voltage motor inverter topologies.

In addition to the keynotes, the conference comprises a series of technical sessions. One presentation will analyze passive component characterization, highlighting methods for extracting parasitic inductance and capacitance at frequencies above 100 MHz and demonstrating the influence of these non-idealities on converter stability. Another session will detail automated dynamic characterization of SiC and GaN power devices, showing how double-pulse test rigs can be synchronized with high-speed digitizers to reduce measurement uncertainty and to capture fast recovery behavior.

Electromagnetic compatibility topics are covered in two dedicated talks. The first provides practical guidance on the use of near-field probes for pinpointing radiated emission sources and for validating the effectiveness of EMI filter designs. The second demonstrates a complete conducted emission measurement workflow on a small-scale prototype, using a Line Impedance Stabilization Network (LISN) together with a modern mixed signal oscilloscope. The presenter will also outline a filter design methodology that exploits the time-frequency capabilities of the instrument.

A further webinar addresses the growing need for accurate efficiency measurement in data center and AI server power supplies. By employing precision power analyzers capable of tracking distorted waveforms and rapid load transients, participants will learn how to obtain true input and output power values that satisfy 80 PLUS certification requirements.

The last session focuses on harmonic current and voltage flicker compliance for low-voltage, grid-connected products. The speaker will review the limits and test procedures defined in IEC/EN 61000-3-2/-3-3 and IEC/EN 61000-3-12/-3-11, and will demonstrate how integrated compliance testing software linked to a power analyzer can deliver automated pass/fail decisions from early prototype evaluation through to final type approval.

Speakers include subject matter experts from Rohde & Schwarz, Hitachi, Infineon, PE-Systems, Würth Elektronik, and the Universities of Bremen and Zaragoza. Their contributions combine academic insight with industrial experience, providing attendees with both theoretical background and hands-on measurement strategies.

The conference is free of charge, but registration is required. The full agenda, speaker biographies and the registration portal are available at: http://www.rohde-schwarz.com/power-electronics-conference

The post Rohde & Schwarz to host Power Electronics Online Conference “From Design to Validation” in May appeared first on ELE Times.

• Introducing the ST64UWB family: the first fully integrated ultra-wideband (UWB) solution supporting IEEE 802.15.4z and upcoming IEEE 802.15.4ab UWB standard with multi-millisecond ranging (MMS), including narrow-band assistance radio (NBA)
• ST64UWB family delivers industry-leading RF performance leveraging ST’s 18 nm FD-SOI technology
• Best-in-class performance enables new use cases and enhances user experience for automotive, smart home, and smart building applications

STMicroelectronics (NYSE: STM), a global semiconductor leader serving customers across the spectrum of electronics applications, introduces an ultra-wideband (UWB) chip family that comprehensively supports the next-generation wireless standard for localizing and tracking devices at distances up to several hundred meters. This UWB chip family combines extended range with greater processing power and robustness to enable new and improved automotive, consumer, and industrial use cases, including secure digital access control, presence and motion sensing, and precise approach detection.

“The ST64UWB family we announce today is an industry-first system-on-chip supporting the latest ultra-wideband specification, IEEE 802.15.4ab, including narrow-band assistance radio, with ultra-precise ranging and sensing,” said Rias Al-Kadi, General Manager, Ranging and Connectivity Division, STMicroelectronics. “These chips are tailored for automotive, consumer, and industrial applications, providing innovators with a powerful platform for the next wave of ultra-wideband use cases.”

The emerging standard builds on the IEEE 802.15.4z UWB wireless technology in today’s hands-free digital car keys that unlock a vehicle on approach. New technical enhancements enabled by multi-millisecond ranging (MMS) and narrowband assistance (NBA) extend operating range, strengthen connections with devices carried in bags or rear pockets, and enable direction finding at close range to better interpret user intent. IEEE 802.15.4ab also enhances radar mode, improving use cases such as child presence detection (CPD) in vehicles, a potentially life-saving feature recommended by Euro-NCAP, the independent vehicle safety assessment organization.

The devices are now sampling to major Tier 1s and original equipment manufacturers.

Why IEEE 802.15.4ab and ST64UWB matter

“IEEE 802.15.4ab is set to become the backbone of next-generation ultra-wideband,” said Andrew Zignani, Senior Research Director at ABI Research. “By 2030, we expect the vast majority of ultra-wideband-equipped vehicles to migrate to this new standard, leveraging a rapidly growing installed base of hundreds of millions of compatible smartphones. Meanwhile, backward compatibility with IEEE 802.15.4z allows the industry to adopt these enhancements quickly without disrupting existing deployments, while enabling valuable new user experiences and services across multiple end markets.”

“IEEE 802.15.4ab is the foundation for enabling a new generation of key fobs as part of a digital key system,” said Daniel Siekmann, Head of Car Access HW D&D Team, Forvia Hella. “It offers more than eight times the range of 802.15.4z and significantly better non-line-of-sight performance, which allows for key fob functionality to reliably perform from a back-pocket or inside a bag. With backward compatibility to 802.15.4z, it provides a practical path to replace legacy HF/LF key fobs with a modern ultra-wideband-based architecture, a transition that is further enabled by STMicroelectronics’ new ST64UWB chips.”

“By adopting 802.15.4ab, car access systems can simultaneously improve performance, cost efficiency, and robustness. The more than eightfold increase in range effectively mitigates back-pocket and other obstructed-signal conditions. At the same time, backward compatibility with 802.15.4z gives OEMs like LGIT the flexibility to either enhance reliability using their existing fixed reference points or reduce the number of reference points to lower overall system cost,” said William Jung, Team Leader, LG Innotek.

“With IEEE 802.15.4ab, the ability to drastically increase UWB performance, especially when the smartphone is left in the rear pocket, is highly appreciated,” said Bernd Bär, Expert Product Line Technology, Marquardt. “At the same time, operating within tight global homologation limits while remaining backward compatible with existing IEEE 802.15.4z ecosystems tremendously extends the applicability of UWB systems.”

“Over the last decade, Nuki has helped establish and shape the smart lock category in Europe. We firmly believe Ultra-Wideband is a transformative technology for precise, hands-free unlocking,” said Jürgen Pansi, Chief Innovation Officer, Nuki Home Solutions. “Together with STMicroelectronics and their ST64UWB solution, we are showcasing how the IEEE 802.15.4ab standard can bring the power of Aliro and UWB to our region.”

Further information for editors

The three SoCs introduced today (ST64UWB-A100, ST64UWB-A500, and ST64UWB-C100) are built on 18 nm FD-SOI process that boosts link budget by nearly 3dB versus standard bulk technologies, extending range by roughly 50% beyond the gains already delivered by the IEEE 802.15.4ab standard.

The ST64UWB-A series, designed for automotive applications and starting with the ST64UWB-A100 for use cases such as digital key and precise vehicle localization, features an Arm® Cortex®-M85 core and supports ASIL A(B) automotive safety concept. The ST64UWB-A500 adds AI acceleration and digital signal processing to support edge AI-powered radar applications, including child presence detection (CPD), kick sensing, and outward-facing use cases, such as parking sensors and radar-based vehicle-sentinel mode. These radar capabilities benefit from the new 15.4ab Kaiser pulse shape and the upgraded 1.3 GHz bandwidth of UWB channel 11, resulting in twice the accuracy compared to 500 MHz channels.

The ST64UWB-C100, built on an Arm Cortex-M85 core, targets commercial and consumer applications, delivering best-in-class hands-free and tap-free user experiences with full Aliro standard compatibility.

ST is accelerating next-generation UWB adoption with a comprehensive development kit including a UWB stack (PHY/MAC), a radar toolbox, development boards, a reference design for antennas, and application examples for both automotive and consumer markets. Find out more on product specification and 802.15.4ab technology at www.st.com/uwb

About STMicroelectronics

At ST, we are 48,000 creators and makers of semiconductor technologies, mastering the semiconductor supply chain with state-of-the-art manufacturing facilities. An integrated device manufacturer, we work with more than 200,000 customers and thousands of partners to design and build products, solutions, and ecosystems that address their challenges and opportunities, and the need to support a more sustainable world. Our technologies enable smarter mobility, more efficient power and energy management, and the wide-scale deployment of cloud-connected autonomous things. We are on track to be carbon neutral in all direct and indirect emissions (scopes 1 and 2), product transportation, business travel, and employee commuting emissions (our scope 3 focus), and to achieve our 100% renewable electricity sourcing goal by the end of 2027. Further information can be found at www.st.com

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The latest annual report from CSconnected confirms that the compound semiconductor cluster in South Wales continues to expand its economic contribution, now supporting £436m of gross value-added (GVA) and 3140 jobs across Wales...

Григорій Синиця: "Інтереси України мають бути понад усе" Інформація КП вт, 04/21/2026 - 13:00

AXT Inc of Fremont, CA, USA — which makes gallium arsenide (GaAs), indium phosphide (InP) and germanium (Ge) substrates and raw materials at plants in China — intends to offer and sell shares of common stock in a public offering. In connection with the offering, the firm also expects to grant the underwriters a 30-day overallotment option to purchase up to an additional 15% of the shares offered in the public offering price, minus the underwriting discounts...

Ordered a SOT323 diode instead of a SOD323, worked out in the end. Just had to make sure not to let pin 2 touch the exposed ground plane submitted by /u/circuitsable [link] [comments]

InPHRED Inc of Boston, MA, USA (a developer of next-generation photonics solutions for consumer sensing and digital health that was founded in 2023 at Yale University) has announced its formal expansion into the data-center optical interconnect market, extending its nanoporous platform into high-speed connectivity solutions for next-generation AI infrastructure...

I made this little piano using an ATtiny85 and a some push buttons. All 12 keys are read through a single ADC pin using a resistor-ladder voltage divider. Each button taps a different point in the chain, so the voltage tells the chip which key is down. Functional but quite limited as only one key really works at a time. This was my first project to learn the ATtiny85 and I'm happy with how it turned out. Sounds pretty rough though. submitted by /u/RAZK0M [link] [comments]

submitted by /u/ruumoo [link] [comments]

Applied Optoelectronics Inc (AOI) of Sugar Land, TX, USA (a designer and manufacturer of optical and hybrid fibre-coaxial networking products for AI data centers, cable TV and broadband fiber access networks) plans to expand its Houston-area footprint through the addition of two adjacent buildings in Pearland, Texas, adding about 388,000ft2 of manufacturing capacity...

Applied Optoelectronics Inc (AOI) of Sugar Land, TX, USA (a designer and manufacturer of optical and hybrid fibre-coaxial networking products for AI data centers, cable TV and broadband fiber access networks) received a new $71m order for 800G single-mode data-center transceivers in early April from one of its major hyperscale customers. This marks $124m in orders from this customer since mid-March, which will more than double the existing backlog from this customer...

Three smart home hubs, from two different companies. All supporting both 2.4 GHz Wi-Fi and proprietary 900 MHz wireless links. How do they differ, and are similar? Let’s find out.

Last month, I told you about TP-Link’s Tapo Hubs and their functional similarity to Blink’s Sync Modules. And last week, I took apart Blink’s second-generation hub, comparing it to its premiere predecessor which’d gone “under the knife” nearly a decade earlier. Today, I’ll be dissecting the entry-level Tapo H100 hub I conceptually covered in late March.

How comparable (or not) is its design to those of its Blink competitors? Let’s dive in and see.

Smart hub brothers from different mothers?

I shared a full set of outer box shots last month; so to avoid redundancy, this time I’ll show only the perspective that’s different, since last month’s device remains in ongoing use while this one (with a different serial number) is intended (initially, at least) solely for dissection.

As usual, it’s accompanied by a 0.75″ (19.1 mm) diameter U.S. penny for size comparison purposes. Also note that, per the common “US/1.26” notation on the sticker found on the bottom of both boxes, this device and last month’s H100 are presumably based on the same hardware version.

Opening up the packaging, you’ll find a sliver of literature inside, with our patient below it.

The only constant is change

On the product support page I initially referenced earlier, you’ll also discover that there have been four hardware versions to date: v1.0, v1.2, my v1.26, and the subsequent (I’m assuming) v1.8. Attempts to mix-and-match divergent hardware, as I’ve noted before, can be problematic. That said, most households will contain only a single hub device (versus multiple sensors and other “smart” peripherals), minimizing the potential-problem set size in this particular case.

Before continuing, let’s revisit the backside of the device, this time zooming on the markings.

Notice what looks like a label stuck on top of part of the original info? That’s exactly what it is.

As it turns out, the FCC ID found on the backside markings (2AXJ4H100) was also later updated; it’s now 2BH7FH100. Are the two changes related? Dunno.

Time to dive inside, a task that, compared to TP-Link smart switches of (recent) past, was thankfully fairly straightforward this time around.

Inside the front half of the enclosure, you’ll find a speaker (used, for example, to implement the sound emitted when the hub is paired with, and activated by, a “smart” doorbell).

And the mechanical assembly for the pairing-and-reset switch is shown on one side, as seen earlier.

Categorizing the guts

Here, however, is the view that most of you are most interested in, I guess.

The bottom half of the PCB disconnected itself from the back half of the enclosure while I was prying apart the two halves.

Further bending back the PCB reveals how the AC “prongs” connect to it.

As well as the PCB backside itself.

The small five-lead IC in the middle, PCB-labeled U4, is marked:

TACeY1

Its identity is unknown to me (readers?). Below it, in a larger seven-lead package, is On-Bright Electronics’ OB2512NJP offline primary-side-regulation (PSR) power switch. Below that is a M7 high voltage rectifier diode. And to its left is another (bridge and three-lead, this time) rectifier, Galaxy Microelectronics’ MBF10M.

Back to the PCB front side, after “un-popping” the PCB (putting it back in its normal place within the enclosure, which is upside down in both the prior-version and the following photo versus its normal orientation).

Note first the two antennae, one embedded and along the lower edge, the other discrete and along the right side. I assume one’s for 2.4 GHz Wi-Fi while the other supports TP-Link’s proprietary 900 MHz ISM band “ultra-low power wireless protocol”. Reader suggestions as to which is what are greatly appreciated in the comments.

In the upper right (again, lower left in normal operating orientation) is the status LED, which ends up shining out the device front cover. The pairing-and-reset switch is along the left side. The top half of the PCB, perhaps obviously given the sizeable transformer, houses the AC/DC conversion circuitry (the fact that the AC prongs are directly behind it at the rear of the device is another functional tipoff).

And, last but not least, the various ICs. In the lower right corner of the transformer is an Eon Silicon Solution EN56Q64-104HIP 64 Mbit serial flash memory, which we’ve seen before in both higher and lower capacities. I assume it houses the code for Realtek’s RTL8710CM SoC below and to its left, also found in the first two of the three TP-Link smart switches I’ve dissected so far. At the bottom, in the middle, is WayTronic’s WT588F02B audio DSP with an integrated DAC, which “can directly drive 8R 0.5W speakers”, an unsurprising function given the speaker connection directly to the left of it. Above and to the right of the audio DSP is another IC I can’t ID:

35UT
53C1

And above and to the left of the mono speaker connector is one final mystery:

300A
S992
515

Reader insights into any of the chips I was unable to identify, as well as broader thoughts on anything I’ve discussed here, are always welcome in the comments.

Brian Dipert is the associate editor, as well as a contributing editor, at EDN.

Related Content

• The Tapo Hub: TP-Link joins the low-bandwidth, long-range RF club
• The Blink Sync Module 2: Faster response and local storage, too
• Teardown: Security camera network module
• TP-Link’s Kasa HS103: A smart plug with solid network connectivity
• TP-Link’s Kasa EP10: If at first it doesn’t connect, buy, buy again

The post TP-Link’s Tapo H100: Smart sensing unencumbered appeared first on EDN.

Ketone detection may sound like the domain of biochemistry, but at its core, it’s also an electronics challenge: how do we translate a chemical presence into a measurable electrical signal?

The key lies in the ability of circuits to convert molecular interactions into quantifiable outputs. Through principles like signal conversion, amplification, and conditioning, electronics transform invisible chemical activity into reliable data, making ketone monitoring practical and accurate while underscoring how deeply electronics shape modern health technologies.

Ketones: Small molecules, big impact

Ketone detection is crucial because these molecules act as direct indicators of how the body manages its energy balance. Moderate levels can reflect healthy states such as fasting, exercise, or adherence to ketogenic diets, while dangerously high concentrations may signal conditions like diabetic ketoacidosis that require urgent medical attention.

By providing timely and accurate measurements, ketone monitoring empowers individuals to optimize nutrition and performance and gives clinicians essential data to prevent and manage metabolic complications. In both everyday wellness and clinical care, reliable ketone tracking plays a decisive role in safeguarding health.

Overview of ketone detection sensors

Nowadays ketone detection has moved well beyond the lab bench and into lifestyle and wearable electronics. Compact analyzers are being built into fitness trackers, smartwatches, and portable health devices, giving users real-time insights into metabolism and diet. This evolution is powered by the fundamentals of electronics—miniaturization, low-power design, and signal processing—that make complex biochemical measurements practical in everyday life, turning health monitoring into a seamless part of daily routines.

While electronics provide the backbone for translating chemistry into measurable signals, the choice of sensor defines how ketones are detected. Electrochemical sensors generate currents via redox reactions, optical sensors capture variations in light absorption or fluorescence, and chemiresistive sensors—including semiconductor gas sensors—exploit surface-level conductivity shifts. Each technology offers a unique pathway from molecular interaction to electrical output, setting the stage for circuits to amplify, filter, and interpret the data with precision.

Ketone sensing: The gold standard and beyond

In practice, blood testing is the clinical gold standard, using the enzyme β-hydroxybutyrate dehydrogenase (HBDH) to generate a precise electrical signal from β-hydroxybutyrate (BHB). Keep note that a blood ketone meter functions as a miniaturized potentiostat; it maintains a fixed voltage across the biosensor to measure the current produced by this reaction, providing the data needed to distinguish safe ketosis from metabolic crisis.

Figure 1 Today’s multifunction blood meter kits provide a fast and reliable method for measuring β-ketone, blood glucose, and other parameters from fresh whole blood samples in just a few simple steps. Source: eLinkCare

However, the field is evolving beyond the invasive finger-prick. Researchers are now optimizing alternative biomarkers and delivery methods to bridge the gap between clinical accuracy and user convenience.

Exhaled breath analysis targets acetone—a volatile byproduct of fat metabolism. Current technologies, such as chemiresistive metal-oxide sensors, offer a high-frequency, non-invasive “proxy” for ketosis. While breath analysis currently lacks the clinical precision required for acute emergencies like diabetic ketoacidosis (DKA), it provides a sustainable, pain-free alternative for routine wellness tracking.

In a nutshell, ketone breath analyzers typically employ semiconductor-based, chemiresistive sensors to detect acetone—a byproduct of fat metabolism—in exhaled breath. These sensors function by measuring changes in electrical resistance triggered by volatile organic compounds (VOCs), which serves as a proxy for blood ketone concentration. High-end models often integrate CMOS technology to enhance both sensitivity and measurement precision.

Figure 2 Ketone breath analyzers and subcutaneous sensors deliver real-time feedback on ketosis levels. Source: Author

Continuous ketone monitoring (CKM) is an emerging technology that utilizes a small subcutaneous sensor—similar to a continuous glucose monitor (CGM)—to measure BHB levels in the interstitial fluid. By providing real-time data and automated alerts, these devices aim to detect rising ketone levels before they escalate into metabolic emergencies, effectively transitioning patient care from ‘spot-check’ diagnostics to continuous, proactive health management.

Note that a subcutaneous sensor is a tiny, flexible filament inserted into the fatty tissue just beneath the skin. By monitoring the interstitial fluid in this layer, the sensor uses enzymes to measure specific chemical markers—like glucose or ketones—and converts those readings into a continuous digital stream. Because it stays in place for several days and does not require venous access, it offers a painless, real-time alternative to repeated finger-prick testing.

Electronic biosensing for makers

To wrap this up, remember that while the medical industry uses highly proprietary, pre-calibrated systems, the underlying principle is a fantastic playground for makers.

Whether you are working with a glucose oxidase strip for blood sugar or a β-hydroxybutyrate strip for ketone levels, the principle is the same: enzyme-mediated reactions generate electrons that must be measured against a stable reference potential.

Once you master the transimpedance amplifier (TIA), you have essentially built the core of a professional-grade diagnostic instrument. In fact, most commercial biosensors integrate the TIA and supporting circuitry into an analog front end (AFE), which delivers low-noise performance and simplifies design, an approach that makers can emulate at smaller scale when experimenting.

On a related note, amperometry is the electrochemical technique at the heart of most biosensor strips. It involves applying a fixed potential to an electrode and measuring the resulting current, which is directly proportional to the concentration of the analyte.

In glucose oxidase strips, the enzymatic reaction produces hydrogen peroxide that is oxidized at the electrode, while in β-hydroxybutyrate strips, NADH transfers electrons through a mediator. In both cases, the transimpedance amplifier converts this tiny current into a usable voltage signal, enabling accurate, low-noise measurement.

Figure 3 Quick view shows a closeup of a standard ketone blood tester strip. Source: Author

For those curious about non-chemical ketone monitoring, it’s worth noting that hobbyists have also experimented with MQ13x series gas sensors such as MQ138 to approximate acetone levels in breath.

These gas sensors are not medical-grade and require careful calibration against known standards, but they can respond to volatile organic compounds in exhaled breath. Pairing one with a microcontroller, a stable heater supply and signal conditioning circuitry give you a rough, experimental ketone breath analyzer. It’s a fun proof-of-concept project—ideal for learning sensor physics and electronics.

Figure 4 MQ138 sensor module helps detect acetone in exhaled breath, enabling experimental DIY ketone analysis. Source: Author

Just keep in mind that for any real-world health tracking, these DIY setups should be for educational exploration only. Medical-grade devices undergo extensive clinical validation to handle variables like hematocrit levels, temperature, and signal interference—factors that a prototype might miss.

Finally, do not let the complexity of biomedical electronics intimidate you. Every expert once started as a novice tinkering with circuits and sensors. Dive in, experiment boldly, and let curiosity be your guide—the frontier of electronic biosensing is wide open for makers willing to explore.

T. K. Hareendran is a self-taught electronics enthusiast with a strong passion for innovative circuit design and hands-on technology. He develops both experimental and practical electronic projects, documenting and sharing his work to support fellow tinkerers and learners. Beyond the workbench, he dedicates time to technical writing and hardware evaluations to contribute meaningfully to the maker community.

Related Content

• What’s in store for optical biosensors?
• The critical role of sensors in medical devices
• Designer’s guide: Sensors for medical applications
• Developing medical sensors compliant with global requirements
• Tools and techniques for electrical characterization of biosensors

The post Electronic biosensing: A quick take on ketone detection appeared first on EDN.

Market analyst firm TrendForce forecasts that the global AI-focused optical transceiver market will rise at more than 57% year-on-year from US$16.5bn in 2025 to $26bn in 2026, as it has entered a phase of rapid growth. This surge is driven not only by specification upgrades but also reflects a broader structural reshaping of the optical communications supply chain amid accelerating AI data-center deployment...

The UK Semiconductor Centre (UKSC) has appointed Brian Robertson as director of international partnerships to lead on strengthening the UK’s global position in semiconductors and deepening connections between the UK ecosystem and international partners...

Tried to use it to light some LED’s though I think the circuit expects a battery voltage to use as feedback as it has very low output current otherwise. Short circuit current was 300mA submitted by /u/ram_the_socket [link] [comments]

Current setup 😅 ESP32 + RFID + SDR + random modules Not sure if this will fully work yet… But it’s getting interesting 👀 Any ideas what I should add next? submitted by /u/AppropriatePen283 [link] [comments]

There must be a T48 UV erasing addon with the EPROM blank check. 270-280nm 800mW diode. submitted by /u/nerovny [link] [comments]