smartphone

94 Articles

Blood Pressure Monitor For Under $1

June 20, 2023 by 22 Comments

Medical equipment is not generally known for being inexpensive, with various imaging systems usually weighing in at over a million dollars, and even relatively simpler pieces of technology like digital thermometers, stethoscopes, and pulse oximeters coming in somewhere around $50. As the general pace of technological improvement continues on we expect marginal decreases in costs, but every now and then a revolutionary piece of technology will drop the cost of something like a blood pressure monitor by over an order of magnitude.

Typically a blood pressure monitor involves a cuff that pressurizes against a patient’s arm, and measures the physical pressure of the blood as the heart forces blood through the area restricted by the cuff. But there are some ways to measure blood pressure by proxy, instead of directly. This device, a small piece of plastic with a cost of less than a dollar, attaches to a smartphone near the camera sensor and flashlight. By pressing a finger onto the device, the smartphone uses the flashlight and the camera in tandem to measure subtle changes in the skin, which can be processed in an app to approximate blood pressure.

The developers of this technology note that it’s not a one-to-one substitute for a traditional blood pressure monitor, but it is extremely helpful for those who might not be able to afford a normal monitor and who might otherwise go undiagnosed for high blood pressure. Almost half of adults in the US alone have issues relating to blood pressure, so just getting information at all is the hurdle this device is attempting to overcome. And, we’ll count it as a win any time medical technology becomes more accessible, more inexpensive, or more open-source.

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Hackaday Links: May 7, 2023

May 7, 2023 by 39 Comments

More fallout for SpaceX this week after their Starship launch attempt, but of the legal kind rather than concrete and rebar. A handful of environmental groups filed the suit, alleging that the launch generated “intense heat, noise, and light that adversely affects surrounding habitat areas and communities, which included designated critical habitat for federally protected species as well as National Wildlife Refuge and State Park lands,” in addition to “scatter[ing] debris and ash over a large area.”

Specifics of this energetic launch aside, we always wondered about the choice of Boca Chica for a launch facility. Yes, it has all the obvious advantages, like a large body of water directly to the east and being at a relatively low latitude. But the whole area is a wildlife sanctuary, and from what we understand there are still people living pretty close to the launch facility. Then again, you could pretty much say the same thing about the Cape Canaveral and Cape Kennedy complex, which probably couldn’t be built today. Amazing how a Space Race will grease the wheels of progress.

Continue reading “Hackaday Links: May 7, 2023” →

Using An Old Smartphone In Place Of A Raspberry Pi

April 27, 2023 by 62 Comments

The Raspberry Pi was a fairly revolutionary computing device when it came on the scene around a decade ago. Enough processing power to run a full Linux desktop and plenty of GPIO meant almost certain success. In the past year, though, they’ve run into some issues with their chip supplier and it’s been difficult to find new Pis, which has led to some looking for alternatives to these handy devices. [David] was hoping to build a music streaming server and built it on an old smartphone instead of the ubiquitous single-board computer.

Most smartphones are single-board computers though, and at least the Android devices are fully capable of running Linux just like the Pi. The only problem tends to be getting around the carrier or manufacturer restrictions like a locked bootloader or lack of root access. For [David]’s first try getting this to work, he tried to install Navidrome on a Samsung phone but had difficulties with the lack of memory and had to build the software somewhere else and then load it on the phone. It did work, but the stock operating system kept killing the process for consuming too much memory.

Without root access, [David] decided to try LineageOS, a version of Android which, among other benefits, is typically much more configurable than the stock version of Android that is shipped with smartphones. This allowed him to disable or uninstall anything not needed for his music server to free up enough memory. After some issues with transcoding the actual music files he planned on streaming, his music server was successfully up and running on a phone that would have otherwise been relegated to the junk drawer. The specific steps he took to get this working can be found on his GitHub page as well.

[David] also mentioned looking at PostmarketOS for this job which is certainly a viable option for some, but the Linux distribution for phones is only supported on a few devices. Another viable alternative for a project like this if no Raspberry Pis are available might be any of a number of Pine64 devices that might also be sitting around gathering dust, like the versatile Linux-based Pinephone.

Glowscope Reduces Microscope Cost By Orders Of Magnitude

March 24, 2023 by 15 Comments

As smartphones become more ubiquitous in society, they are being used in plenty of ways not imaginable even ten or fifteen years ago. Using its sensors to gather LIDAR information, its GPS to get directions, its microphone to instantly translate languages, or even use its WiFi and cellular radios to establish a wireless hotspot are all things which would have taken specialized hardware not more than two decades ago. The latest disruption may be in microscopy, as this build demonstrates a microscope that would otherwise be hundreds of thousands of dollars.

The microscope is a specialized device known as a fluorescence microscope, which uses a light source to excite fluorescent molecules in a sample which can illuminate structures that would otherwise be invisible under a regular microscope. For this build, the light is provided by readily-available LED lighting as well as optical filters typically used in stage lighting, as well as a garden-variety smartphone. With these techniques a microscope can be produced for around $50 USD that has 10 µm resolution.

While these fluorescence microscopes do have some limitations compared to units in the hundred-thousand-dollar range, perhaps unsurprisingly, they are fairly impressive for such a low-cost alternative. More details about these builds can also be found in their research paper published in Nature. Even without the need for fluorescence microscopy, a smartphone has been shown to be a fairly decent optical microscope, provided you have the right hardware to supplement the phone’s camera.

Rollercoasters Are Triggering The IPhone’s Crash Detection System

October 12, 2022 by 68 Comments

Apple has been busy adding new features to its smartphone and smartwatch offerings. Its new iPhone 14 and Apple Watch 8 now feature a safety system that contacts emergency services in the event the user is in a automobile accident.

As with so many new technologies though, the feature has fallen afoul of the law of unintended consequences. Reports are that the “crash detection system” is falsely triggering on rollercoasters and in other strange circumstances. Let’s take a look at how these systems work, and why this might be happening.

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A Raspberry Pi Phone For The Modern Era

October 10, 2022 by 43 Comments

While it might seem like mobile phones are special devices, both in their ease of use and in their ubiquity in the modern culture, they are essentially nothing more than small form-factor computers with an extra radio and a few specific pieces of software to run. In theory, as long as you can find that software (and you pay for a service plan of some sort) you can get any computer to work as a phone. So naturally, the Raspberry Pi was turned into one.

[asherdundas], the phone’s creator, actually found a prior build based around the Raspberry Pi before starting this one. The problem was that it was built nearly a decade ago, and hadn’t been updated since. This build brings some modernization to the antiquated Pi phone, and starts with a 3D printed case. It also houses a touchscreen and a GSM antenna to connect to the cell network. With some other odds and ends, like a speaker and microphone, plus a battery and the software to tie it all together, a modern functional Raspberry Pi phone was created, with some extra details available on the project page.

The phone has the expected features — including calling, texting, and even a camera. A small WiFi USB dongle allows it to connect to the Internet too, allowing it to do all of the internet browsing a modern smartphone might want to do. The only thing that it might be pretty difficult to do is install Android apps, and although there are ways to get Android apps working in Linux, it’s not always strictly necessary to have this functionality.

Powering A Cellphone With Gasoline

September 1, 2022 by 24 Comments

Batteries are a really useful way to store energy, but their energy density in regards to both weight and volume is disappointing. In these regards, they really can’t compete with fossil fuels. Thus, [bryan.lowder] decided to see if he could charge a phone with fossil fuels as safely and inoffensively as possible.

Obviously, with many national grids relying on fossil fuels for a large part of their generation, most of us are already charging our phones with fossil fuels to some degree. However, the aim here was to do so more directly, without incurring transmission losses from the long runs through the power grid. Continue reading “Powering A Cellphone With Gasoline” →