PIN photodiode collects, counts, and discriminates alpha energies to determine residences’ radon gas-caused cancer danger degrees. Back in late July, when I was working on last month’s published piece on radon gas analysis, I longed to see what was inside the battery-operated sensing device I’d recently started using. But I resisted the temptation to fire up the spudger and screwdriver set, because: I’d bought it myself, for $100+, and I intended to continue using it long-term, since radon gas concentrations vary over time. Even if I trusted my ability to disassemble it and then put it back together again in still-full-functional form (which I don’t), I didn’t want to interrupt the data-logging cadence even briefly. But Providence seemingly intervened on my behalf, as counterbalance to my reticence. Less than a week after my post appeared, a PR contact from Chinese company X-Sense, who swore she hadn’t even seen my coverage yet, reached out to see if I was interested in reviewing its latest consumer-tailored smart radon alarm, the just-introduced XR0A-iR. The device is so new that it only showed up on the company website a few days ago, as I write this on September 10, 2026. Spooky, eh? I accepted the invitation with the as-usual qualifiers in such situations: that the company would not see my coverage until it appeared in publicly published form on EDN’s website, and that X-Sense would have no ability to influence the content either in-advance or post-publication. The PR contact agreed. I also asked for two units; one for hands-on testing (for which I planned to recruit my next-door neighbor, both because he didn’t have one yet and because I wanted to get a non-techie’s take on activation and ongoing use) and the other to satisfy my own teardown curiosity. Smart equals pervasive data access X-Sense agreed again. And late last month, two units showed up at my front door. My next-door neighbor successfully activated his yesterday; stay tuned for his hands-on observations to come in a future post. And that same (yester)day, I took the other one apart. X-Sense is a smart home device manufacturer of which I wasn’t previously aware. The company’s products are analogous to those (for example) of TP-Link, whose Kasa and Tapo temperature, humidity and fluid leak sensors I’ve dissected in recent months. X-Sense already had two radon sensors in its product portfolio, the XR0A-SR and higher-end XR0B-SR, but they’re standalone-use units. The XR0A-iR is its first “connected” radon-related product. I’ll as-usual start with some outer box shots, accompanied by a 0.75″ (19.1 mm) diameter U.S. penny for size comparison purposes. Top. Front. Left side. Back. Right side. And bottom. Packet secrets The first thing you’ll see after removing the box lid is a comprehensive and consumer-comprehensible (those adjectives rarely get used together, in a positive sense, at least!) user guide. Underneath it is our patient. Surrounded by two mysterious baggies. I jest; they’re not mysterious, because they’re labeled. One, containing silica gel, I commonly encounter to absorb humidity, thereby keeping the electronics dry. The other, marked as indicating that inside it was activated charcoal, was a bit more of an initial head-scratcher. But then I recalled the mail-in radon lab test (mentioned in my prior writeup) that my wife and I ordered prior to purchasing our home a decade-plus ago, and which looked something like this. I rattle sound-suspected at the time, and subsequent research has confirmed, that inside it was activated charcoal, used both for short-duration testing and (interestingly, at least to me) for filtering radon out of well water. That said, it’s not recommended for ongoing residential-air radon gas cleansing purposes. Here, I’m guessing, it absorbs ambient radon gas at warehouses and retailer shelves that would otherwise end up on the device’s sensor, adversely affecting subsequent initial-powerup measurement results in the process. Onward. Here’s our patient, now freed from its previous cardboard captivity. Top (note the grille; hold that thought). Front.
